How to Water Tomatoes in Extreme Heat

Overheating of the Soil and Root System

Tomato roots work most actively when the soil temperature is 18–25°C (Kotov, 2016). When the soil warms above 30°C, root growth slows down, and at 35°C and above, it practically stops (Jones, 2008). The absorptive capacity of root hairs drops sharply. The plant begins to "starve" even when nutrients are present in the soil because the roots simply cannot absorb them.

Roots are especially vulnerable on hot afternoons when the topsoil can heat up to 45–50°C. Under such conditions, protein structures in root cells begin to break down, and recovery takes several days even after the temperature drops.

Impaired Calcium Uptake

Calcium is an element that moves through the plant only with the water flow (transpiration stream). In heat, when the plant closes its stomata to retain moisture, water movement slows down. Calcium stops reaching young tissues and fruits (Akhatov, 2010; Heuvelink, 2018).

This is exactly what causes blossom-end rot—a dark spot on the blossom end of the fruit. There may be plenty of calcium in the soil, but the plant cannot deliver it where it is needed. Large-fruited varieties and hybrids are particularly sensitive to this.

Pollen Sterility and Flower Drop

Tomato is a self-pollinating plant, but the pollination process is very sensitive to temperature. When daytime temperatures exceed 32°C, pollen becomes sterile, and at 35°C and above, it dies (Jones, 2008; Welbaum, 2015).

The optimal temperature for tomato pollination is 20–25°C during the day and 15–20°C at night. If nighttime temperatures exceed 22°C, the energy accumulated during the day is spent on respiration rather than on fruit set. As a result, flowers are poorly pollinated, fruit sets do not form, and the plant drops flowers to conserve resources for survival (Akhatov, 2010; Kotov, 2016).

Sunscald on Fruits

Tomato fruits, especially those lacking sufficient leaf cover, can suffer from sunscald. Pale, later whitish or yellowish spots appear on the surface. The tissue under such a spot becomes dry and leathery. Later, secondary infections easily enter these spots, and the fruit rots (Akhatov, 2010; Swiader, 1992).

Fruits that are exposed to the sun after leaf removal (pruning, trimming) and those hanging over the edge of the bed without protection from neighboring plants are most vulnerable.

What the Numbers Say

Tomato is a warm-climate plant, but it has clear physiological limits. The optimal daytime temperature range for growth and fruiting is 18–27°C, and nighttime 16–18°C (Akhatov, 2010; Kotov, 2016). The soil temperature should ideally remain within 18–22°C (Jones, 2008).

As soon as these values are exceeded, problems begin. The table below clearly separates the consequences for air and soil.

Table. Critical Temperature Thresholds for Tomato

Night Heat Is No Less Dangerous

Many gardeners focus only on daytime heat. But for tomatoes, nighttime temperature is often the deciding factor. If the air does not cool below 20–22°C at night, the plant cannot recover from daytime stress. Intensive nighttime respiration consumes sugars that should have gone into fruit growth. As a result, fruits are smaller, and overall yield decreases (Akhatov, 2010; Kotov, 2016).

Pay special attention to nighttime temperatures in greenhouses, where the air cools more slowly than in open ground.

Soil Temperature — The Hidden Enemy

Tomato roots work like a "pump": they absorb water and minerals. But this pump overheats. At soil temperatures above 30°C, root hairs die off, and absorption drops sharply (Jones, 2008). At 35°C and above, the process practically stops. The plant begins to wilt even when the soil is moist because the roots cannot take up the water.

This is one of the main reasons why "little by little" watering does not help in heat—the water simply evaporates from the surface without reaching the active root zone, and the roots in the overheated top layer are unable to absorb it.

How to Tell If the Heat Is Already Dangerous for Your Tomatoes

Do not wait for leaves to curl or flowers to drop. Here are simple signs indicating heat stress:

• Leaf rolling along the central vein (especially at noon) — a protective reaction that reduces evaporation.
• Loss of turgor — leaves become "cloth-like," although the soil is moist.
• Whitening or yellowing of individual fruits on the sunny side.
• Appearance of dark spots on the blossom end of fruits (blossom-end rot) — even if it was not there before.
• Dropping of flowers and small fruit sets despite abundant flowering.

If you notice at least one of these signs, the temperatures have already reached a dangerous level, and it is time to take active measures to save the harvest.

When to Water: Morning Is the Best Time

In hot weather, it is best to water tomatoes early in the morning, right after sunrise or within the first 2–3 hours of daylight (Akhatov, 2010; Heuvelink, 2018). There are several reasons for this:

• By morning, the soil has cooled overnight, so water does not evaporate instantly and has time to penetrate deeply.
• Morning watering gives the plants a supply of moisture for the whole day when evaporation is at its peak.
• Moisture on the leaves has time to dry before the intense heat sets in, reducing the risk of fungal diseases (especially in greenhouses).
• Water that reaches the root zone in the morning cools the soil and protects the roots from overheating during the midday hours.

Evening watering in heat is acceptable but only as an exception—when morning watering was not possible. However, evening watering increases nighttime air humidity, which in greenhouses can trigger the development of gray mold and other fungal infections (Kotov, 2016). If you water in the evening, do it 2–3 hours before sunset so that the water has time to soak in and the leaves can dry.

Watering at noon, when the sun is at its zenith, is categorically not recommended. Water droplets on leaves act like magnifying glasses, intensifying sunscald. In addition, most of the water evaporates from the soil surface without reaching the roots, and cold water on overheated soil causes root shock (Jones, 2008).

How Much Water: The Norm per Plant

An adult fruiting tomato in hot weather consumes 2 to 3 liters of water per day (Heuvelink, 2018; Jones, 2008). This is an average figure that can vary depending on plant size, fruit load, soil type, and weather.

However, watering daily with 2–3 liters per plant is wrong. This approach only moistens the top layer of soil, not reaching the bulk of the roots. Tomato roots go down to 1–1.5 meters, and most of them are at a depth of 30–60 cm (Akhatov, 2010; Swiader, 1992). Therefore, watering should be generous but infrequent.

Practical recommendation for the hot period:

• On sandy and sandy-loam soils: 10–15 liters per plant once every 2–3 days.
• On loamy and clay soils: 15–20 liters per plant once every 3–4 days.

These volumes allow water to penetrate to a depth of 40–60 cm, where the main absorbing roots are located. In between waterings, the top layer dries out, which is not a problem, while moisture is retained at depth.

How to Increase the Depth of Wetting

The main goal of watering in heat is not to wet the surface, but to deliver water deep down to the roots. Here is how to achieve this:

1. Increase the duration of watering. Instead of giving small amounts over 10–15 minutes, water once but for a long time—30–40 minutes—so that the water has time to penetrate deeply.

2. Make a basin or furrow around the plant. Form a small earthen ridge around the stem and water directly into this basin. The water does not spread over the surface and is directed downward.

3. Use drip irrigation with a long cycle. If you have a drip irrigation system, increase the cycle duration during hot weather, not the frequency. For example, instead of three short 20-minute waterings, do one long one—60–90 minutes. This allows deep soil layers to be saturated (Heuvelink, 2018).

4. Check the wetting depth. An hour after watering, dig a small hole next to the plant and see how deep the moisture has penetrated. Ideally, the wet layer should reach 40–50 cm. If it is less, increase the water volume or watering time.

5. Water not only the root collar area. Tomato roots spread far beyond the canopy, especially in open ground. Moisten an area about 60–80 cm in diameter around the plant to cover the entire root system.

Rely on the Plants' Condition

The best indicator of a proper watering regime is the plants themselves. On a hot afternoon, leaves may droop slightly—this is a normal response to high temperature. But if turgor does not recover by evening, there is not enough moisture.

Also, pay attention to the growth rate of fruits. If the fruits have stopped increasing in size during heat and new fruit sets are not forming, the plants are likely suffering from a lack of moisture, despite apparent watering.

Remember the rule: in heat, watering should be not frequent, but deep and generous. Deep moistening is exactly what allows roots to remain in a cool, moist environment and continue working even when the air is scorching.

Surface Moistening Leads to Root Overheating

The bulk of the absorbing roots of a tomato lie at a depth of 30–60 cm (Akhatov, 2010; Swiader, 1992). If you water with 1–2 liters per plant several times a day, the water simply does not reach that depth. It stays in the topsoil—the zone that heats up to 40–50°C in the heat (Jones, 2008; Heuvelink, 2018).

As a result, the roots remain in a hot, dried-out environment, while the moisture you supply either evaporates from the surface or is absorbed by thin surface roots, which work poorly in heat. The plant continues to suffer from thirst, and you wonder why it wilts despite frequent watering.

Key point: roots need moisture at depth, where the soil temperature is 5–10°C lower than at the surface. Only deep watering creates a moist and cool layer there, protecting the root system from overheating.

Formation of Soil Crust

Frequent but scant waterings lead to the formation of a dense crust on the soil surface. This crust:

• Prevents air from reaching the roots (root respiration worsens);
• Slows further water infiltration—water simply runs off to the sides or evaporates;
• Cracks when drying, damaging thin surface roots.

Breaking the crust by loosening in hot weather is difficult and risky—you can damage the roots that have come close to the surface in search of moisture.

Aeration Suffers

Tomato roots, like all plant organs, need oxygen for respiration. Frequent small waterings keep the topsoil constantly wet, displacing air from soil pores (Kotov, 2016). Roots begin to suffocate, and their absorptive capacity drops even further. The plant wilts not so much from heat as from oxygen starvation.

With deep but infrequent watering, the soil has time to aerate between waterings, and roots receive both water and air.

Stimulation of a Shallow Root System

The plant always grows toward water. When you water superficially, roots develop mainly in the topsoil (0–20 cm) rather than growing deep (Akhatov, 2010). This makes tomatoes even more vulnerable to heat, because the top layer dries out and overheats the fastest.

Deep watering, on the other hand, "trains" roots to grow downward, into cooler and more moisture-stable horizons. Such plants tolerate drought and high temperatures much more easily.

Water Loss to Evaporation

Every time you apply water from above, a significant portion evaporates from the soil surface, especially on a hot, windy day. With surface watering, the water use efficiency is extremely low—up to 30–40% of moisture simply goes into the air. With deep watering, evaporation losses are minimal.

Risk of Disease Development

In greenhouses and even in open ground, frequent small waterings create increased humidity in the ground-level air, especially if water gets on the leaves. This encourages the development of fungal diseases—late blight, alternaria, gray mold (Kotov, 2016). In hot weather, it would seem fungi have difficulty reproducing, but nighttime dew and residual moisture from evening watering create favorable conditions for them.

In Short: Three Reasons to Avoid Frequent Small Waterings

1. Water does not reach the main roots — the plant continues to suffer from root overheating.

2. Shallow roots develop instead of deep ones — the plant becomes more vulnerable to drought.

3. The soil is waterlogged on top but remains dry below — roots cannot choose where it is best.

Practical Conclusion

In hot weather, water tomatoes rarely but very generously. It is better to give 15–20 liters per plant once every 2–3 days than to pour 3–5 liters daily. This way, you provide moisture to the deep layer, protect roots from overheating, and keep the plants healthy.

How Mulch Helps in Heat

A mulching layer performs several important functions at high temperatures:

• Reduces soil temperature by 5–10°C compared to bare ground (Jones, 2008; Heuvelink, 2018).
• Reduces evaporation of moisture from the surface, allowing water to remain longer in the root zone.
• Prevents the formation of soil crust, which impedes air and water penetration.
• Suppresses weed growth, which competes with tomatoes for moisture.
• Protects surface roots from direct solar heating.

The choice of mulching material is crucial: some materials work well in hot weather, others poorly or even harmfully.

Comparison of Mulching Materials for Hot Periods

Why Black Plastic Film Is a Bad Choice in Heat

Black plastic film, which works well in spring to warm the soil, becomes dangerous for tomatoes in summer heat (Welbaum, 2015; Swiader, 1992). It absorbs solar heat and transfers it to the soil, which can increase soil temperature by 5–8°C above that of bare ground.

As a result, roots are in a scorching environment, stop absorbing water and nutrients, and plants wilt even with abundant watering. If you use black film, it must be shaded with light-colored material (e.g., straw or mown grass) during hot periods to reduce heating.

How to Choose Mulch for Heat

For protection against overheating, light-colored and loose materials that reflect sunlight and do not hinder the evaporation of excess moisture are best:

1. Straw — the best choice for open ground. A layer of 10–15 cm reliably protects roots from overheating and retains moisture.

2. Light-colored mulch (white agrotextile) — for greenhouses and southern regions.

3. Compost — a universal option that both cools and nourishes.

4. Mown grass (must be dried) — an accessible material but requires regular renewal.

Mulching Rules in Heat

For mulch to work effectively, follow a few simple rules:

• Apply mulch to moist soil. Water the plants generously before mulching.
• Do not place mulch right up to the stem. Leave a 5–7 cm gap around the stem to avoid rotting of the root collar (Kotov, 2016).
• Renew mulch as needed. Grass and straw compact and lose their properties over time. Add a fresh layer.
• The layer should be sufficient. For grass and straw — 8–15 cm, for compost — 5–7 cm, for light-colored mulch, one layer of material is enough.

Mulch and Watering: How They Work Together

Mulch and proper watering complement each other:

• Deep watering delivers water to the roots.
• Mulch retains this water in the soil and prevents evaporation.
• Mulch protects roots from overheating, and deep watering creates a moist "reservoir" in the lower soil layers.

Together, these two techniques allow tomatoes to survive even prolonged periods of extreme heat.

When Shading Is Really Needed

Shading tomatoes is not always necessary, only in certain situations:

• Daytime temperatures consistently stay above 32–35°C for several days in a row (Jones, 2008).
• Fruits show sunscald — pale or yellowish spots appear on the sunny side.
• Leaves lose turgor even with moist soil — a sign that evaporation exceeds root capacity.
• Plants are in a greenhouse, where glass or polycarbonate intensifies heating and natural ventilation is insufficient (Akhatov, 2010; Kotov, 2016).
• Tomatoes grow on poor, sandy soils that dry out and overheat quickly.

In temperate climates, shading is usually needed only in the hottest months—July and August. In southern regions (e.g., steppe zones, Central Asia), shading may be necessary throughout the growing season (Welbaum, 2015; Swiader, 1992).

It is important to understand: shading protects plants but reduces photosynthesis. Therefore, it should be used moderately, creating diffused light rather than complete shade.

What to Use for Shading: Materials and Methods

Different materials are used for shading tomatoes. Here are the main options:

What Percentage to Shade

The optimal shading level for tomatoes in heat is 30–50% of full sunlight (Heuvelink, 2018; Jones, 2008). With such shading, leaf temperature drops by 3–5°C, and fruit temperature drops by 5–8°C, preventing burns and preserving fruit quality.

If shading exceeds 50%, the plant begins to suffer from lack of light: stems elongate, leaves become pale, fruits ripen more slowly, and sugar content decreases. In greenhouses with dense foliage, additional strong shading can cause "etiolation"—weakening of plants (Jones, 2008).

How to Position Shading Correctly

• In open ground, place the net or cover above the plants at a height of 1.5–2 m so that air circulates freely. Leave the sides open for ventilation.
• In greenhouses, apply shading to the roof (whitewash, external net). Internal shading screens are less effective because they trap heat inside, but can be used additionally (Akhatov, 2010).
• Direction of shading in open ground should preferably be from the south and southwest, where the sun is most aggressive in the afternoon.

What to Do If Shading Is Not Available

If there is no way to install a net or whitewash the greenhouse, you can use simple techniques:

• Leave more leaves when pruning—they themselves shade the fruits (Kotov, 2016).
• Do not remove lower leaves until fruiting begins—they protect the soil and roots from overheating.
• Plant tomatoes with rows oriented north–south—this provides more even lighting throughout the day.

Main Rule: Shading Is Not a Substitute for Watering

Shading reduces heating but does not compensate for lack of moisture. During hot periods, be sure to combine shading with deep watering and mulching. Only an integrated approach will protect tomatoes from heat stress.

Features of the Greenhouse Microclimate in Heat

In the enclosed or semi-enclosed space of a greenhouse, heat affects plants more strongly than outdoors:

• Air temperature is higher than outside, especially in the upper part of the greenhouse where hot air rises. The difference can reach 5–10°C (Akhatov, 2010; Kotov, 2016).
• Air humidity rises due to evaporation from the soil surface and leaves, especially after watering. This creates a favorable environment for fungal diseases.
• Stagnant air intensifies overheating because warm air is not removed and hot leaves are not cooled.
• Glass and polycarbonate transmit sunlight but trap thermal radiation (greenhouse effect), intensifying heating.

All these factors require a different approach to watering than in open ground.

Ventilation — The Most Important Part of the Watering Strategy

Without proper ventilation, watering in a greenhouse can be useless or even harmful. Moist, stagnant air creates ideal conditions for diseases and does not help plants cool down.

Basic rules of ventilation in heat:

1. Open all available vents (transoms) to create a draft and remove overheated air. Modern greenhouses use automatic opening systems (Jones, 2008; Kotov, 2016).

2. Turn on fans to mix the air. Horizontal air flow (HAF) helps even out temperature and humidity inside the greenhouse and within the plant itself (Jones, 2008).

3. Combine watering and ventilation: water early in the morning, then ventilate the greenhouse so that excess moisture evaporates rather than condenses.

4. In extreme heat, use evaporative cooling systems (fogging, wet pads), but only in combination with ventilation to avoid excessive humidity (Akhatov, 2010; Jones, 2008).

How to Adjust Watering in a Greenhouse

In a greenhouse, watering must be especially precise, because there is no natural rainfall and evaporation is more intense.

• Water early in the morning before the greenhouse warms up. This gives plants a supply of moisture for the day and allows leaves to dry before the heat sets in.
• Use drip irrigation — it is most effective in greenhouses because it delivers water directly to the root zone without wetting the air and leaves (Heuvelink, 2018; Kotov, 2016).
• The watering volume in a greenhouse should be higher than in open ground due to higher evaporation. An adult fruiting plant in a greenhouse can consume up to 3–4 liters of water per day at peak heat (Jones, 2008; Heuvelink, 2018).
• Check substrate moisture at a depth of 10–15 cm. Use a hand probe or simply dig with your finger. If the soil is dry at that depth, it is time to water.

Remember that in greenhouses with substrates (mineral wool, coco, peat), watering management is different: more frequent but measured watering is needed, along with mandatory drainage monitoring to avoid salinization (Heuvelink, 2018).

Air Humidity Control

Relative air humidity in a greenhouse for tomatoes should be maintained within 60–70% (Kotov, 2016; Akhatov, 2010). In heat and high humidity (above 80%), problems arise:

• Condensation on leaves and fruits creates an ideal environment for fungal diseases—gray mold, late blight, cladosporiosis.
• Evaporation from leaves decreases, and the plant overheats because it cannot cool through transpiration.
• Pollen becomes sticky and does not shed, impairing pollination and fruit set (Akhatov, 2010; Jones, 2008).

How to manage humidity:

• Moderate watering — do not overwater the soil to avoid evaporation of large volumes of water.
• Ventilation — the main way to reduce humidity. Open vents and turn on fans.
• Do not water in the evening in the greenhouse if high humidity is expected at night—this can cause condensation and disease development.
• Use air heating on cool nights to prevent dew from forming on plants (Kotov, 2016).

Practical Recommendations for a Greenhouse in Heat

Important Addition

In a greenhouse with intensive watering and high temperatures, root overheating in substrates (e.g., in bags or pots) is possible. To avoid this, try to keep the substrate in the shade and not heated by direct sunlight. Use light-colored mulch or white bags instead of black ones (Jones, 2008).

Also, in a greenhouse, it is important to monitor the electrical conductivity (EC) of the soil solution: with insufficient watering and high temperature, salts concentrate, and roots cannot absorb water even if it is present. This condition is called "physiological drought." At the first signs of wilting, check the EC and, if necessary, flush the substrate with clean water (Heuvelink, 2018).

Step 1. Assess the Level of Threat (the Day Before or Early Morning)

Before acting, understand how serious the situation is. Rely not only on the weather forecast but also on the condition of the plants:

• Leaves are curled and have lost turgor by 9–10 a.m. — a sign that the heat will be critical.
• White or yellowish spots have appeared on fruits (sunscald).
• Nighttime temperatures do not drop below 22°C for several days in a row (this is especially dangerous because the plant does not recover overnight) (Jones, 2008; Akhatov, 2010).
• The soil at a depth of 5–10 cm is dry and hot (you can check by hand).

If at least one of these signs is present, move to active measures.

Step 2. Perform Emergency Deep Watering (Early Morning, Before 8–9 a.m.)

On the day when extreme heat is expected, be sure to do deep watering before the intense heat sets in.

• Rate: 15–20 liters per adult plant (in a greenhouse, up to 25 liters, depending on bush size and soil type) (Heuvelink, 2018; Swiader, 1992).
• How to water: slowly, so that the water soaks deep rather than running off the surface. Use basins or furrows.
• Why: the moist deep soil layer will act as a "thermal buffer"—roots will remain cool and able to absorb water even at noon when the top layer has dried out.

Important: do not water with cold water from a well or borehole! The water temperature should be close to the soil temperature (20–25°C), otherwise roots will suffer shock and stop working (Jones, 2008). If the water is very cold, fill containers in advance and let it warm up in the sun.

Step 3. Apply or Refresh Mulch (Immediately After Watering)

If you do not have mulch yet, apply it urgently. If you do, check the layer and add more if necessary.

• Best material in heat: light-colored straw, hay, mown grass (dried), compost, light-colored agrotextile. The layer should be at least 10–15 cm for straw and 5–7 cm for compost (Welbaum, 2015).
• Do not use black film or dark cover material—they increase soil heating.
• Why: mulch reduces evaporation, prevents soil overheating, and retains moisture in the root zone.

Step 4. Shade the Plants (Before the Peak Heat)

If you do not have permanent shading, install it before the sun gets high.

• For open ground: stretch a shading net (30–50%) over the beds at a height of 1.5–2 m.
• For a greenhouse: whitewash the glass or polycarbonate with a chalk solution, stretch an external net, or use internal screens.
• Why: shading reduces leaf and fruit temperature by 3–8°C, prevents sunscald, and reduces evaporation (Akhatov, 2010; Jones, 2008).

Important: shading should not be too dense (more than 50–60%), otherwise plants will not get enough light for photosynthesis. The optimal level is 30–50%.

Step 5. Ensure Ventilation (Especially in a Greenhouse)

In a greenhouse during extreme heat, ventilation is a matter of life and death for the plants.

• Open all vents, transoms, and doors. Create a draft.
• Turn on fans. If you have an evaporative cooling system (fogging, wet pads), use it—but only together with ventilation to avoid excessive humidity (Kotov, 2016).
• In open ground, make sure air does not stagnate between plants. If necessary, thin the foliage or remove lower leaves to improve circulation.

Step 6. During the Day — Only Observation and Targeted Help

In the middle of the day (from 11 a.m. to 4 p.m.), do not water and do not perform any active work with the plants. The only exception is an extreme emergency (e.g., plants begin to wilt en masse).

• If plants start to wilt severely even with moist soil, you can do a refreshment spraying of the leaves with water from a fine sprayer to lower leaf temperature. But this must be done very carefully, in full shade, and only if air humidity is low; otherwise, you can provoke burns or fungal diseases (Jones, 2008; Akhatov, 2010).
• In a greenhouse, with severe wilting, you can turn on fogging for short cycles (5–10 minutes) with simultaneous ventilation.

Step 7. In the Evening — Re-inspection and Adjustment

After sunset, when the heat subsides, inspect the plants:

• If the leaves have not regained turgor by evening, there was not enough moisture. Increase the watering volume the next morning.
• If signs of blossom-end rot appear on fruits, this indicates calcium deficiency due to poor uptake. In heat, this often happens even if you applied calcium. You can do a foliar feed with calcium nitrate (0.5–1%) on the leaves in the evening hours (Heuvelink, 2018).
• Check the condition of the mulch: if it has matted or thinned, add a fresh layer.

Step 8. Repeat the Algorithm Daily Until the Heat Subsides

Extreme heat lasts for several days. Maintain the regime:

• Daily deep morning watering.
• Maintaining mulch in good condition.
• Daily ventilation (in a greenhouse) and humidity control.
• Shading during the sunniest hours.

Important: do not reduce the watering volume if the heat persists—plants consume more water, not less. During prolonged heat (a week or more), you can increase the interval between waterings to 3 days, but the water volume per watering should remain large (15–20 L) to keep the deep soil layer moist.

Step 9. After the Heat Subsides — Recovery

When the heat begins to subside, do not stop care abruptly.

• Gradually reduce the watering volume, returning to the normal regime.
• If you used shading, remove it gradually so that plants adapt to full light.
• Carry out a preventive treatment against fungal diseases, because after heat and watering, plants are weakened and vulnerable (Kotov, 2016).
• Feed the plants with potassium-phosphorus fertilizers for recovery (Heuvelink, 2018).

Quick Reference Card for Extreme Heat