How to Stay Cool in a Heatwave: 8 Science-Based Strategies

• Hydration with Water + Electrolytes
• Pre‑Cooling & Per‑Cooling Techniques
• Intermittent Fanning and Shade
• Dress Smart
• Timing Outdoor Activity
• Heat Acclimation
• Home Cooling Modifications
• Avoid Diuretics
• Summary Table
• References

Heatwaves are increasing in frequency and intensity due to climate change, posing acute and cumulative risks to human health. Beyond dehydration and heat exhaustion, prolonged high temperatures can contribute to heat cramps, heat syncope, and even life-threatening heat stroke—especially in vulnerable populations such as the elderly, young children, and individuals with chronic medical conditions.

The body regulates its internal temperature primarily through sweating and blood flow to the skin; however, these mechanisms can be overwhelmed when ambient temperatures and humidity remain high, resulting in thermal strain and cardiovascular stress 

This comprehensive guide outlines 8 evidence-based strategies to help you maintain thermoregulation, conserve hydration, and reduce heat-related health risks—empowered by scientific understanding and practical tips to stay safe during extreme heat.

1. Hydration with Water + Electrolytes

Maintaining proper hydration isn’t just about quenching thirst—it's a critical physiological support system during heat stress. As temperature rises, sweating increases, leading to fluid and electrolyte losses that can exceed 2 L/hour in intense conditions. This fluid loss reduces plasma volume and impairs heat circulation to the skin, raising heart rate (cardiovascular drift) and core temperature.

Cardiovascular strain, alongside reduced sweat production, diminishes the body’s ability to manage thermal load.

Evidence suggests drinking to match sweat-rate losses (~±2% of body weight) provides optimal thermal and cardiovascular protection and prevents hyponatremia. Plain water lowers fluid volume—but doesn’t replenish sodium, potassium, magnesium, or calcium—vitally needed to maintain nerve conduction, muscle function, and fluid retention. Low electrolyte levels can cause muscle cramps, dizziness, or worse during heatwaves.

• Why it matters: Heat and sweat lead to hypohydration, increasing cardiovascular strain and core temperature—hindering thermoregulation and physical performance.

• Optimal intake: During high temperatures or activity, aim for consistent hydration—about 250 mL (8 oz) every 15–20 minutes.

• Electrolyte addition: Sweating depletes not just water but also sodium, potassium, magnesium, and calcium—which are vital for fluid retention and muscle/cognitive function .

• Practical tip: Sip 250 mL every 15–20 minutes in heat or activity; use low‑sugar oral rehydration formulas or lightly salted water to maintain electrolyte balance.

2. Pre-Cooling & Per-Cooling Techniques

Lowering your core temperature before heat exposure (pre‑cooling) and during exertion (per‑cooling) enhances heat tolerance and performance. Pre‑cooling using methods like cool-water immersion or cooling vests reduces resting core and skin temperature, delaying thermal strain and cardiovascular fatigue.

Targeted per‑cooling—applying cold to the head, neck, or face—can be practical and effective. Studies show such localized cooling reduces skin temperature, improves thermal sensation, and enhances endurance and sprint performance. Although cooling the head/face alone is less effective than neck-targeted cooling, combining these sites produces meaningful heat relief without large, heavy equipment.

• Flooding your body with cool fluid before exposure lowers core and skin temperature, increasing heat tolerance.

• Targeted cooling (head/neck/face): Keeping these areas cool significantly improves thermal comfort and endurance performance in heat.

• Practical tip: Before heading out, splash cool water on your neck and head or wear a damp cloth or scarf. If exercising outdoors, carry a water spray for intermittent cooldowns.

3. Intermittent Fanning and Shade

Airflow and shade drastically improve comfort in a heatwave. In dry climates, moving air over damp skin enhances sweat evaporation—the body’s primary cooling method. Fans effectively lower skin temperature and perceived heat, especially when used with damp cloths or misting systems.

Passive shade structures like parasols or trees block solar radiation—responsible for significant heat gain—without requiring power. These simple interventions lower surrounding air temperature and reduce direct heat load on the body.

• Fans and ventilation: Circulating air enhances sweat evaporation and cooling—especially effective in dry environments .

• Passive methods (e.g. parasols, shades): Minimising exposure to radiation lowers both ambient and body temperature.

• Practical tip: Use fans and ventilation indoors and outdoors. When outdoors, seek shade under trees or umbrellas, and use misting devices where possible.

4. Dress Smart

Wardrobe choices can significantly influence heat management. Loose-fitting, breathable fabrics (e.g., cotton or linen) facilitate airflow and enhance evaporative cooling through sweat. Light colours reflect sunlight, reducing radiative heat gain.

Covering sun-exposed areas with ventilated wide-brimmed hats protects against solar radiation on the scalp and face. Clothing with moisture-wicking technology further enhances comfort during exertion.

• Choose lightweight, loose-fitting, and light-coloured clothing to reflect sunlight and enhance airflow.

• Wide-brimmed hats with ventilation protect your face and scalp from solar load.

• Practical tip: Wear multiple light layers rather than one thick layer. Combine breathable fabrics, moisture management, and sun protection for maximum comfort.

5. Timing Outdoor Activity

The hottest hours—typically 11 am to 4 pm—strain the body’s cooling system and significantly increase heat-related illness risk. Exercise or chores during these hours elevate core temperature and place stress on thermoregulation.

Instead, schedule outdoor activities during early morning or evening when temperatures are lower. Pair this with strategies like light cooling before and breaks during exertion.

• Avoid peak sun hours (11 am–4 pm).

• If exercising or gardening, do so in the early morning or late evening, with pre-cooling or intermittent cooling breaks (fans, cool cloths).

• Practical tip: If you must be active midday, stay hydrated, work or exercise in the shade, and take regular breaks indoors or in cool areas.

6. Heat Acclimation

Through repeated exposure to heat, the body adapts: sweat rate increases, sweat onset occurs earlier, cardiovascular strain reduces, and core temperature thresholds shift upward. Controlled heat exposure (e.g., walking in shade, mild exercise) over 10–14 days enables acclimation.

Though most research focuses on athletes, low-level exposure also benefits the general public—reducing heat-induced cardiovascular drift and improving comfort during daily activities.

• Gradual exposure to warm conditions with controlled training increases sweat output and lowers heart rate and core temperature over time.

• Practical tip: During a heatwave, spend 30 minutes outdoors in shade or mild sun for the first few days, increasing gradually. Don’t push; acclimation is about controlled tolerance.

7. Home Cooling Modifications

Passive design techniques can significantly reduce household heat strain without air conditioning. Features such as shading windows, reflective roofing, and insulation cut down on solar gain. Closing windows and blinds during daylight traps cooler night air inside, while opening them in the evening flushes built-up heat. Fans placed to draw in cool night air or exhaust daytime heat improve airflow and comfort.

Community cooling centres are essential safety nets for individuals without access to effective cooling at home, reducing hospital admissions and heat-related mortality.

• Passive design (e.g. shading, light-coloured roofs/windows) can lower indoor heat gain significantly.

• Night-time ventilation flushes out heat from the structure, cooling the environment for the next day .

• Community cooling centres offer refuge for those lacking household cooling, especially in heatwaves.

• Practical tip: Pre-darken your home during the morning, use reflective shades, and ventilate at night. Know your area’s cooling centre locations.

8. Avoid Diuretics

Drugs and beverages that promote fluid loss—like caffeine, alcohol, and diuretics—can worsen dehydration during heatwaves. They impair fluid retention, weaken thermoregulation, and may compound heat-related illness risk.

• Caffeine and alcohol may worsen dehydration; opt instead for water, coconut water, or oral rehydration solutions.

• Practical tip: Limit caffeine and alcohol. Focus on water and electrolyte-rich beverages; herbal teas, coconut water, and low-sodium sports drinks are good substitutes.

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Summary Table

Focus Area	What to Do
Hydration	Sip water + electrolytes consistently, ~250 mL every 15 min in heat
Cooling tactics	Pre-cool, use fans, damp or shade gear, and cooling collars
Timing	Avoid peak heat hours; schedule activities early or late
Clothing	Dress in light, loose, breathable, and reflective layers
Acclimation	Gradually expose yourself to mild heat daily for 10–14 days
Home design	Shade windows, ventilate at night, use reflective materials
Community	Know where cooling centres are located and how to access them
Avoid diuretics	Limit caffeine/alcohol; hydrate wisely with electrolyte-enhanced drinks

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References

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2. Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390. https://doi.org/10.1249/mss.0b013e31802ca597

3. Armstrong, L. E. (2000). Performing in extreme environments. Comprehensive Physiology. https://pubmed.ncbi.nlm.nih.gov/32136119

4. Castle, P. C., Macdonald, A. L., Philp, A., Webborn, A., Watt, P. W., & Maxwell, N. S. (2010). Pre-cooling leg muscle improves intermittent sprint exercise performance in hot, humid conditions. Journal of Applied Physiology, 109(4), 1093–1100. https://doi.org/10.1152/japplphysiol.00315.2010

5. Cao, Y., Lei, T.-H., Wang, F., Yang, B., & Mündel, T. (2022). Head, face and neck cooling as per-cooling modalities to improve exercise performance in the heat: A narrative review and practical applications. Sports Medicine – Open, 8, 16. https://doi.org/10.1186/s40798-022-00411-4

6. Gagnon, D., & Kenny, G. P. (2012). Critical core temperature at fatigue is higher in untrained than trained individuals during exercise in the heat. Journal of Applied Physiology, 113(9), 1420–1427. https://pubmed.ncbi.nlm.nih.gov/23007042

7. McCubbin, A. J., et al. (2020). Influence of beverage temperature and menthol on ad libitum fluid intake and endurance performance in the heat. International Journal of Sport Nutrition and Exercise Metabolism, 30(4), 282–289. https://doi.org/10.1123/ijsnem.2019-0169

8. Minett, G. M., Duffield, R., Marino, F. E., & Portus, M. (2012). Mixed-method pre-cooling improves cycling capacity in the heat. European Journal of Applied Physiology, 112, 3111–3122. https://doi.org/10.1007/s00421-012-2261-4

9. Palmer, C. D., Sleivert, G. G., & Cotter, J. D. (2021). Effects of head and neck cooling on thermoregulation, pacing, and performance. Australian Journal of Physiology, 32(2 Suppl 1), 122P. https://pubmed.ncbi.nlm.nih.gov/33903662

10. Baker, L. B. (2017). Sweat rate and sweat sodium concentration in athletes: A review of methodology and intra/inter-individual variability. Sports Medicine, 47(Suppl 1), 111–128. https://doi.org/10.1007/s40279-017-0704-z

11. González-Alonso, J., et al. (1999). Influence of body temperature on the development of fatigue during prolonged exercise in the heat. Journal of Applied Physiology, 86(3), 1032–1039. https://pubmed.ncbi.nlm.nih.gov/10066725

12. Jay, O., & Kenny, G. P. (2010). Heat exposure in the elderly: Physiological responses and practical strategies. Environmental Health Perspectives, 118(12), 1499–1504. https://doi.org/10.1289/ehp.1002283

13. Kenny, G. P., & Jay, O. (2013). Thermoregulation, fatigue and exercise performance. Comprehensive Physiology, 3(1), 189–214. https://doi.org/10.1002/cphy.c120027

14. Nelson, R. L., et al. (2014). Cardiovascular drift during exercise in the heat and its effect on stroke volume. Exercise and Sport Sciences Reviews, 42(4), 173–178. https://doi.org/10.1249/JES.0000000000000016

15. Giuriato, G., Pedrinolla, A., Schena, F., & Venturelli, M. (2018). Muscle cramps: A comparison of the two leading hypotheses. Journal of Electromyography and Kinesiology, 38, 160–164. https://doi.org/10.1016/j.jelekin.2017.10.005