Warm weather can make it easier to spend time outdoors, whether you enjoy walking, running, cycling, gardening, playing sports, or exercising in a local park. However, as temperatures and humidity rise, physical activity can place additional strain on your body.
During physical activity, your body produces heat and cools itself through sweating and increased blood flow to the skin. Hot and humid conditions can make this cooling process less effective, increasing the risk of dehydration, heat exhaustion, and heat stroke.
This does not mean you have to stop being active throughout the summer. By checking the conditions, adjusting your routine, staying hydrated, and recognizing early warning signs, you can continue moving while protecting your health.
Before heading outdoors, check the temperature, humidity, local heat warnings, and weather forecast. Pay attention to local alerts so you know when additional precautions may be necessary (Health Canada).
On especially hot days, consider changing when, where, or how you exercise. Early mornings and evenings are often cooler than the middle of the day. You can also choose a shaded trail, an air-conditioned facility, a swimming pool, or another cooler environment.
Air quality matters too. High temperatures and wildfire smoke can sometimes occur at the same time. Check your local Air Quality Health Index, or AQHI, before strenuous outdoor activity and follow the health guidance for your area. The AQHI uses a scale from 1 to 10+ to communicate the health risks associated with local air pollution (Environment and Climate Change Canada).
When wildfire smoke is affecting your community, consider reducing, rescheduling, or moving strenuous outdoor activities indoors, particularly if you develop symptoms or are at greater risk from smoke exposure (Health Canada).
A workout that feels comfortable on a mild day may feel much more demanding in the heat. Reduce your pace, intensity, or duration when conditions are hotter than usual.
For example, you might replace a long run with a shorter walk, reduce the weight or number of repetitions in an outdoor workout, or divide one long session into two shorter periods. Take more breaks than usual and move into the shade whenever possible.
Avoid expecting your usual level of performance during extreme heat. People who are physically active in hot conditions should drink water regularly, take additional breaks, remove unnecessary clothing or equipment, and give their bodies time to recover.
If you are not accustomed to exercising in warm weather, begin gradually. Slowly increasing the length and intensity of outdoor activity can help your body adapt to exercising in the heat.
Do not wait until you feel very thirsty to drink. Thirst may not always provide an early enough warning that your body needs more fluid.
Drink water before you begin exercising and continue drinking regularly during and after your activity. Carry a reusable bottle when walking, cycling, hiking, gardening, or participating in other outdoor activities (Health Canada).
The amount of fluid you need can vary depending on the weather, intensity and length of your activity, your clothing, body size, and how much you sweat. Dark urine, decreased urination, extreme thirst, dizziness, or a dry mouth may be signs that you need to cool down and replace fluids.
Alcohol can contribute to dehydration and may increase the risk of heat-related illness. Be especially cautious about exercising in hot weather after consuming alcohol.
Choose loose-fitting, lightweight, and light-coloured clothing made from breathable materials. A wide-brimmed, breathable hat can provide additional shade for your head, face, and neck.
Use a broad-spectrum, water-resistant sunscreen with a sun protection factor, or SPF, of at least 30. Follow the product instructions and reapply as directed, particularly after swimming, towelling off, or sweating heavily (Health Canada).
Sunscreen can help protect your skin from ultraviolet radiation, but it does not prevent your body from overheating. You still need water, shade, rest breaks, and adjustments to your activity.
Anyone can experience heat-related illness, but certain people may face a greater risk. This includes older adults, people who are pregnant, people with chronic health conditions, people taking certain medications, and those who work or exercise outdoors for long periods.
Your risk may also be higher if you:
• Are recovering from an illness
• Begin exercising while already dehydrated
• Wear heavy clothing or protective equipment
• Have recently consumed alcohol
• Participate in strenuous activity for long periods
Certain medications can affect hydration, sweating, blood circulation, or the body’s ability to regulate temperature. If you have a medical condition or take medication, speak with a doctor or pharmacist about how hot weather may affect you. Do not stop or change medication without professional guidance.
Heat exhaustion can develop when the body becomes too hot and loses fluids through sweating. Warning signs may include:
• Headache
• Dizziness or fainting
• Nausea or vomiting
• Heavy sweating
• Muscle cramps
• Extreme thirst
• Rapid breathing or heartbeat
• Dark urine or decreased urination
• Unusual weakness or fatigue
If you develop these symptoms, stop exercising immediately. Move to a cool or shaded place, remove unnecessary clothing or equipment, and drink water. Do not try to push through the symptoms or finish your workout.
Seek medical advice if your symptoms worsen, do not improve after cooling down and drinking fluids, or you are concerned about your condition.
Heat stroke is a medical emergency. Warning signs may include a high body temperature, confusion, reduced alertness, poor coordination, fainting, and very hot or red skin.
Call 911 immediately if someone shows signs of heat stroke. While waiting for emergency help:
• Move the person to a cooler location, if possible
• Remove unnecessary clothing
• Apply cold water to large areas of the skin or clothing
• Fan the person to help with cooling
• Stay with them until help arrives
Do not leave the person alone or assume that resting will be enough. Immediate cooling and emergency medical attention are necessary.
Some days may simply be too hot or the air quality may be too poor for strenuous outdoor activity. Changing your plan does not mean giving up on your health goals.
Indoor options may include:
• Walking in a shopping centre or indoor track
• Following a home workout or mobility routine
• Visiting a community recreation centre
• Swimming at an indoor pool
• Practising gentle stretching or yoga
• Completing strength exercises at home
• Taking several short movement breaks throughout the day
Adjusting outdoor activities during hot and humid weather and choosing indoor alternatives can help you remain active without taking unnecessary risks.
Staying active supports physical and mental well-being, but your routine should reflect the conditions around you. Check the weather and air quality, exercise during cooler periods, reduce your usual intensity, drink water regularly, and take early symptoms seriously.
There is no benefit to completing a workout if doing so puts your health at risk. On very hot days, choosing a shorter, slower, cooler, or indoor activity can help you remain consistent while protecting your body.
If you have questions about exercising safely with a medical condition or medication, a MembersHealth healthcare professional can help you understand your individual needs and make informed decisions about staying active.