A heat wave is an extended period of extreme heat, often accompanied by high humidity. Prolonged periods of high temperatures and high humidity can be very dangerous for your health. In extreme heat and humidity, evaporation is slowed and your body has to work very hard to maintain a normal temperature.[1] The risks vary depending on your age and health, but by knowing how to prepare for a heat wave and what to do when one occurs, you can avoid the biggest health dangers, such as heat exhaustion and heat stroke.

Part 1
Part 1 of 4:

Preparing Your Family for a Heat Wave

  1. It’s a good idea to have some kind of basic emergency supplies kit prepared and accessible at home. You can keep one kit to cover most possible emergencies. You just need to get together a few household essentials and put them in a secure place in case you should need them. You should have enough supplies to last 72 hours. Make sure your kit includes the following:[2]
    • A gallon of water a day per person (more for nursing mothers, children, and sick people)[3]
    • Non-perishable, easy-to-prepare food, such as salt-free crackers, whole grain cereals, and canned goods -- include a can opener[4]
    • Any medications you need
    • Sanitary and personal hygiene items[5]
    • Infant formula and diapers
    • Pet food
    • A torch or flashlight
    • A first aid kit
    • A cell phone
    • Extra batteries[6]
    • Moist towelettes, toilet paper, and garbage bags for personal sanitation
  2. It’s sensible to think about how you will get in touch with your family if you are separated. One good way to ensure you can get in touch is to write out a contact card for each person with lists of phone numbers and addresses.
    • A contact card is a card where phone numbers are written down and stored somewhere other than your cell phone. A laminated sheet of paper or index card will keep ink from running if it gets wet.
    • If there is high traffic on a phone network, text messages (SMS) are more likely to get through than a call.
  3. If you are in an area that experiences frequent periods of extreme heat, or if you just want to learn some useful skills, you can take a first aid class. Find one in your local area and sign up. Remember that some require payment. Many of the skills you will learn can prove helpful in a heat wave.[7]
  4. Extreme heat can cause health problems for anybody, but there are groups of people for whom it will be more dangerous than others. Young children, older or elderly adults, and sick or overweight people will be at the highest risk of suffering illness due to extreme heat and humidity. People who work outside and athletes may also be at increased risk of heat-related illnesses.
    • If you have somebody in your family who matches any of these descriptions, prioritize helping them.
    • Make sure they understand the dangers of extreme heat.
    • Don't forget pets! If you have a dog or cat, it can be affected by the heat too.
  5. It’s pretty straightforward, but if you want to be prepared for a heat wave, you need to know if there’s one coming and what the predicted temperatures are.[8] Keep up to date with your local weather news, especially if you are in an area that where extreme heat is more common.
    • Sometimes, the power may go out. A hand-cranked or battery-powered radio will help you track the weather forecast.
  6. If you live in an area that is heavily asphalted or covered in concrete, the effects of a heat wave can be increased. Asphalt and concrete store heat longer and gradually release this heat during the night, producing higher night-time temperatures. This is known as the "urban heat island effect".[9]
    • Large cities can be 1.8-5.4F (1-3C) degrees hotter than their surroundings. At night, this difference can be up to 22F (12C) degrees.
    • Stagnant atmospheric conditions and poor air quality (smog, pollution) also exacerbate a heat wave.
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Part 2
Part 2 of 4:

Preparing Your House for a Heat Wave

  1. if you don't have central air-conditioning. Preparing your home for a heat wave involves a number of relatively small tasks that can help you to keep cool air in and hot air out. If you have window air-conditioners, start by making sure they are installed well. If there are gaps around the sides, insulate them.
    • You can get insulating foam panels or spray foam from a home improvement store.[10]
    • You should also make sure the air-conditioning vents and ducts are well insulated.
    • It’s a good idea to repair or replace a faulty air-conditioner before you need to.[11]
  2. One relatively quick thing you can do to help keep your house as cool as possible is to make some reflectors to fit your window panes. Use a reflective material such as tin foil or aluminium foil and wrap it around some cardboard. The foil will reflect the sun rather than absorb it.[12]
    • Put the reflectors between the glass and the window coverings.
    • You might want to do this just for one or two rooms where you will spend a lot of time.
  3. Even with the reflectors, it is a good idea to cover the windows which receive a lot of sun with drapes, shades, awnings, or louvers. Closing the drapes on the inside will make a difference, but outdoor awnings and louvers can reduce the heat that enters a home by up to 80 percent.[13]
    • You can also find heat and light blocking drapes from many department and home improvement stores. These can help keep the room cool.
  4. You can consider keeping your storm windows up all year round. During a heat wave they will help to keep the heat out of your house, just as they help to keep the heat in, and cold out during the winter.[14] They are another layer of insulation between you and the heat outside.
    • Keeping your home as well insulated as possible will help you to stay cool.
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Part 3
Part 3 of 4:

Staying Cool and Hydrated During a Heat Wave

  1. A lot of the health problems that can develop during a heat wave are associated with dehydration, so it’s crucial to make sure you drink plenty of water or a sports drink with electrolytes. Even if you don't feel thirsty, keep taking regular sips. Avoid drinks with a lot of caffeine such as coffee and tea, and severely limit your intake of alcohol.[15]
    • When it is very hot outside, it's recommended that you drink about 4 cups of water per hour.[16] Don't gulp this all at once, though, or you may experience some discomfort.
    • There are some instances when you should consult a doctor before increasing the amount of liquids you drink:
      • If you have epilepsy, or heart, liver, or kidney disease.
      • If you are on a fluid-restricted diet or have a problem with fluid retention.[17]
  2. It’s important to make sure you keep eating, but you should adapt your eating habits to the temperature. Eating is an effective method to control your body temperature. Eat well-balanced and light meals regularly, rather than two or three enormous plates of food. Large meals take more work to digest which will cause your body temperature to increase.
    • Foods that are rich in protein, such as meats and nuts, will increase metabolic heat.[18]
    • Fresh fruit, salads, healthy snacks, and vegetables are good choices.
    • If you're sweating a lot, replace lost salts and minerals as well as water. A handful of salted nuts or pretzels can be a good choice, or drink a sports beverage containing electrolytes or fruit juice.
    • Don’t take salt tablets unless directed to by your doctor.[19]
  3. Keeping out of the sun is the best way to reduce your exposure to the heat. You should identify the coolest room in your house and try to spend as much time there as you can.[20] If your house has more than one story, or you live in a multi-story building, stay on the lowest floor out of the sunshine.[21]
    • Taking cool showers and splashing yourself with cool water is excellent way to lower your body temperature.[22]
  4. If your home is air-conditioned you will really feel the benefit. If not, you might consider spending the warmest part of the day (or even night) in public buildings such as libraries, schools, movie theatres, shopping malls, and other community facilities. Many of these are specially opened by public authorities during a heat wave, so check for extended hours.
    • There are even local cooling centers open in some places to help people cool down. Contact your local power company or do an internet search to find one near you.
    • If you don’t have air-conditioning, even turning on a fan will help to circulate the air a little.
  5. Indoors and out, it is important to remove any heavy clothing and to wear as little as modesty and laws permit. Wear loose-fitting, lightweight, and lightly colored clothing.[23] Natural fabrics such as linen, cotton, and hemp are good choices. Avoid wearing polyester and flannel, as these fabrics will hold in sweat, causing you to stew in the humid air.
    • If you go outside be sure to use at least a 30 SPF sunscreen to avoid sunburn. Protect your head and face with a ventilated, wide-brimmed hat. Wear sunglasses to protect your eyes.[24]
    • Consider wearing clothing made of synthetic sports fabrics that are designed to wick away perspiration.
    • Avoid dark colors, as these absorb the heat.[25]
    • Wear long-sleeved, lightweight clothing when you will be outside to protect yourself from the sun.[26]
  6. Avoid strenuous work or exercise as much as possible. This is especially important during the warmest part of the day, typically 11am to 3pm.[27] If you do have to work outside, use a buddy system so you are not alone. Take frequent breaks and stay hydrated.[28] Pay close attention to how you feel.
    • If your heart is pounding and you're short of breath, stop immediately. Go into a cool environment to rest and drink plenty of fluids.
    • Do not push yourself if you feel like you're becoming overheated. If the heat index is greater than 103F (39.5C), ask about rescheduling nonessential activities for a time when it is not so hot.[29]
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Part 4
Part 4 of 4:

Looking Out for Others During a Heatwave

  1. It’s important to look after others as well as yourself, especially if there are people around you who could be particularly vulnerable to heat-related problems, or may be less able to look after themselves.[30] If you know that a neighbour lives alone and is at risk of health problems from heat (especially where they do not have air conditioning), try to contact family members to come and help.
    • If that is not possible, your local emergency services might be able to help.
    • You can ease the burden just by helping someone stay cool and hydrated.
    • Helping someone reach an air-conditioned place will be beneficial.
  2. Don’t even do this for a brief periods of time. The temperature inside the vehicle can rise to 120ºF (49ºC) or more within minutes, which is hot enough to kill someone very quickly.[31] Keep an eye on pets as well as family members. Make sure they have enough water and shade.
    • If you have accidentally locked your child or pet in the car, contact emergency services immediately.
  3. Keep a close eye on all members of your family and others close to you. Be vigilant and explain to them the importance of taking steps to minimize the effects of heat during a heat wave. One indicator of illness is heat cramps, which are painful spasms in the muscles of the arms, legs, and abdomen. This is most common in people who are dehydrated, sweat a lot, or are not acclimatized to the heat. People who are exercising in heat may also experience heat cramps.[32]
    • Risk factors for heat-related illnesses include strenuous exercise (such as that done by outdoor athletes), lack of acclimatization, poor physical fitness, obesity, and dehydration.
  4. Heat exhaustion is a serious condition and should be treated as soon as possible. There are a number of symptoms to look out for:[33] [34]
    • Cool, clammy skin with "goose bumps"
    • Heavy sweating
    • Fatigue
    • Light-headedness or dizziness
    • Problems with physical coordination
    • Muscle cramps
    • Headache
    • Nausea
  5. Take the person to a cool, shaded place, preferably indoors in air-conditioning. Give the person cool water or a sports drink to drink. Remove excess clothing.[35] If possible, have the person take a cool shower or apply cool towels to the skin to help cool off.[36]
    • The person should start to feel better in about half an hour and experience no long-term effects.
    • Without this treatment the person could develop heatstroke, which is much more serious.[37]
    • If the person shows no signs of improvement after 30 minutes, contact the doctor or emergency services, as the heat exhaustion may be progressing to heatstroke.[38]
  6. Heatstroke occurs when body temperature becomes dangerously high and, no longer able to cool itself, the body begins to overheat. It is a much more serious condition than heat exhaustion, so it’s important to know the signs and know what to do. Call emergency services if you see the following signs, or if a person has been suffering from heat exhaustion for more than 30 minutes:[39]
    • High fever (104F/40C)
    • Severe headache
    • Light-headedness or dizziness
    • Disorientation or confusion
    • Irrational behavior
    • Irritability or emotional instability
    • Nausea or vomiting
    • Muscle weakness and cramps
    • Flushed or red skin
    • Lack of sweating, dry skin
    • Rapid heartbeat
    • Rapid, shallow breathing
    • Seizures
  7. If a person near you has symptoms of heatstroke, the first thing you should do is call emergency services. While you wait for the ambulance, you can take the following steps:[40]
    • Move the person to a cool, shaded area
    • Remove unnecessary clothing
    • Increasing ventilation by using a fan or opening windows
    • Giving the person water to drink, but not medication
    • Shower or immerse their body with cool, but not cold, water that is 59-64°F (15-18°C)
    • Cover the body with cool, damp sheets or towels[41]
    • Apply ice packs to the groin, armpits, neck, and back
  8. If you have a cat or dog, it can also be prone to heat exhaustion or even heat stroke. Watch your pet to make sure that it isn't overheating.[42]
    • If you notice that your dog is panting excessively, give it fresh water right away and move it to a cool, shady place.
    • Drooling is another warning sign of overheating.
    • Feel your pet's body. If it is breathing more rapidly than usual, or if the heart rate is faster than usual, take your pet indoors right away.
    • Animals with flat faces, such as pugs and Persian cats, have more trouble breathing and may be more susceptible to overheating.
    • Paw pads can burn in extreme heat. Use booties or apply a product to your pet's feet to keep them from getting burned on asphalt. If you must walk your pet, try to keep it in grassy areas rather than on roads or sidewalks, which are very hot.
    • Always keep a supply of fresh water outdoors for your pet, and provide plenty of water indoors as well.
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Expert Q&A

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  • Question
    What should I do if I'm camping when it's 97 – 100°F?
    Chris M. Matsko, MD
    Chris M. Matsko, MD
    Family Medicine Physician
    Dr. Chris M. Matsko is a retired physician based in Pittsburgh, Pennsylvania. With over 25 years of medical research experience, Dr. Matsko was awarded the Pittsburgh Cornell University Leadership Award for Excellence. He holds a BS in Nutritional Science from Cornell University and an MD from the Temple University School of Medicine in 2007. Dr. Matsko earned a Research Writing Certification from the American Medical Writers Association (AMWA) in 2016 and a Medical Writing & Editing Certification from the University of Chicago in 2017.
    Chris M. Matsko, MD
    Family Medicine Physician
    Expert Answer
    Try to stay under cover. Stay under a tree or shaded area. Wear clothing that is cotton and breathable. Wear a wide-brim hat, and put on sunscreen with an SPF of at least 30. The American Academy of Dermatology recommends a broad spectrum sunscreen with an SPF of at least 30 that is water resistant.
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Tips

  • During a heat wave, drink 1 liter (0.3 US gal) of water every 2 hours.
  • Don't undertake difficult, hot travel or movement during the daytime. If you must travel, the best time is by night, when it is much cooler.
  • Always pay close attention to those who are at higher risk for heat-related illnesses.
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Warnings

  • Heat waves have been known to start wild-fires and bush-fires across drought-infested areas. Be careful when travelling or living in these areas.
  • Listen to the news, especially news about the heat wave, for any laws passed to combat a drought.
  • Heat waves and "heat storms" (a prolonged and severe heat wave) are to be taken seriously. Use common sense.
  • If there is a drought going on in your area, observe all relevant laws and guidelines, such as not watering the grass or filling up swimming pools.
  • Where you are legally obliged to reduce water usage, you may end up paying severe fines or even prison time if you fail to cooperate.
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  2. http://www.epa.gov/naturaldisasters/extremeheat.html
  3. http://www.ready.gov/heat
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  21. http://www.nhs.uk/Livewell/Summerhealth/Pages/Heatwave.aspx
  22. http://www.disastercenter.com/guide/heat.html
  23. https://www.nlm.nih.gov/medlineplus/heatillness.html
  24. http://www.nhs.uk/conditions/heat-exhaustion-and-heatstroke/pages/introduction.aspx
  25. http://www.mayoclinic.org/diseases-conditions/heat-exhaustion/basics/symptoms/con-20033366
  26. http://www.mayoclinic.org/diseases-conditions/heat-exhaustion/basics/symptoms/con-20033366
  27. http://familydoctor.org/familydoctor/en/prevention-wellness/staying-healthy/first-aid/heat-exhaustion-an-heatstroke.html
  28. http://www.nhs.uk/conditions/heat-exhaustion-and-heatstroke/pages/introduction.aspx
  29. http://familydoctor.org/familydoctor/en/prevention-wellness/staying-healthy/first-aid/heat-exhaustion-an-heatstroke.html
  30. http://familydoctor.org/familydoctor/en/prevention-wellness/staying-healthy/first-aid/heat-exhaustion-an-heatstroke.html
  31. http://familydoctor.org/familydoctor/en/prevention-wellness/staying-healthy/first-aid/heat-exhaustion-an-heatstroke.html
  32. http://www.nhs.uk/conditions/heat-exhaustion-and-heatstroke/pages/introduction.aspx
  33. https://www.aspca.org/pet-care/hot-weather-tips

About this article

Chris M. Matsko, MD
Co-authored by:
Family Medicine Physician
This article was co-authored by Chris M. Matsko, MD. Dr. Chris M. Matsko is a retired physician based in Pittsburgh, Pennsylvania. With over 25 years of medical research experience, Dr. Matsko was awarded the Pittsburgh Cornell University Leadership Award for Excellence. He holds a BS in Nutritional Science from Cornell University and an MD from the Temple University School of Medicine in 2007. Dr. Matsko earned a Research Writing Certification from the American Medical Writers Association (AMWA) in 2016 and a Medical Writing & Editing Certification from the University of Chicago in 2017. This article has been viewed 247,509 times.
38 votes - 87%
Co-authors: 63
Updated: July 29, 2022
Views: 247,509
Article SummaryX

To survive a heat wave, the most important thing is to stay indoors and stay cool. Take cold showers to lower your body temperature and cover windows with reflectors and drapes. Drink plenty of water, as much as four cups an hour if it’s really hot, and eat regular, light meals. Once you’ve taken care of yourself, check on neighbours, family, and friends, prioritising young children and elderly or sick people, who are most vulnerable in the heat. For more tips from our Medical co-author, such as identifying and treating heat exhaustion, read on!

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