An unseasonable heat wave is headed for most parts of British Columbia (BC) this weekend which may take the unprepared by surprise.

The anticipated heat will be an anomaly for this early in May, with temperatures to be 10 C to 15 C degrees above what is normal and heat records are expected to be broken. With that heat wave comes the risk of related emergencies, such as wildfires due to dry brush in wooded areas and flooding from the spring freshet. The heat wave has no chance, however, of reaching the extremes seen during the 2021 “heat dome" that caused many heat-related deaths throughout BC.

Sarah Henderson, scientific director for environmental health services at the BC Centre for Disease Control said that part of the reason for the early warning on the heat this weekend is to give people time to respond and prepare.

“It takes time for the population to get acclimatized to the hot weather each season," she said. “It takes time to physiologically and behaviourally acclimatize."

After a long winter or rainy spring, the first heat wave may feel like a shock to the system because people aren't used to it.

What constitutes a heat warning?

A heat warning is issued when daytime highs and overnight lows are expected to be higher than a predefined threshold that varies by region, and are expected to remain stable for two or more days.

For meteorologists, they look for dangerous patterns where temperatures are increasing day over day for a period of three days or longer. If those temperatures are high and sustained, it can become a hazard to human health.

Henderson said that people who live in buildings without air conditioning may experience greater stress because although temperatures typically drop overnight outside, that might not happen indoors. In those kinds of situations, we need to check-in on those at greater risk for heat illness like infants and young children, Elders and those with respiratory issues to help them prepare for the heat.

Even if this weekend doesn't get to the point where it's too hot, Henderson added “it's an excellent time for everyone to start thinking about an extreme heat emergency in the summer ahead."

Although extreme heat events such as the 2021 heat dome are considered rare (an event happening once or twice every 10 years), these occurrences may increase in frequency in the years to come due to climate change.

What can you do to prepare?

Planning and preparation for these kinds of situations have shown to have better outcomes than responding only after it's already hot. Emergency preparedness should include heat.

If you have air conditioning at home, make sure it is in good working order. If you do not have air conditioning at home:

• Find somewhere you can cool off on hot days. Consider places in your community to spend time indoors such as libraries, community centres, movie theatres or malls. Also, as temperatures may be hotter inside than outside, consider outdoor spaces with lots of shade and running water.
• Shut windows and close curtains and blinds during the heat of the day to block the sun and prevent hotter outdoor air from coming inside. Open doors and windows when it is cooler outside to move that cooler air indoors.
• Ensure that you have a working fan, but do not rely on fans as your primary means of cooling. Fans can be used to draw cooler late-evening, overnight and early-morning air indoors. Keep track of temperatures in your home using a thermostat or thermometer. Sustained indoor temperatures over 31 C can be dangerous for people who are susceptible to heat.
• If your home gets very hot, consider staying with a friend or relative who has air conditioning if possible.
• Identify people who may be at high risk for heat-related illness. If possible, help them prepare for heat and plan to check in on them.

As well, having plenty of drinking water on hand is critical for staying hydrated.

Identify those who are at risk of extreme heat and make that part of community emergency preparedness.

• Elders who are aged 65 or older
• People who live alone
• People with pre-existing health conditions such as diabetes, heart disease or respiratory disease
• People with mental illness including depression and anxiety
• People who are marginally housed
• People who work in hot environments with inadequate air conditioning
• People who are pregnant
• Infants and young children
• People with limited or no mobility

If you find you or somebody you know is getting too warm, go somewhere cooler. You can also have a cool shower or bath, wear a damp t-shirt or towel, or go outdoors to a wooded and shady area.

Anything to draw the heat out of the body is important to prevent heat illness. It is also critical to stay hydrated during a heat event. If you're sweating, you're losing water quickly, and the body cannot regulate temperature without water.

Signs of heat illness

The symptoms of heat-related illness can range from mild to severe. They include:

• Pale, cool, moist skin
• Heavy sweating
• Muscle cramps
• Rash
• Swelling, especially hands and feet
• Fatigue and weakness
• Light headedness and/or fainting
• Headache
• Nausea and/or vomiting

High fever, hallucinations, seizures and unconsciousness can be life threatening and require urgent medical attention. Call 911, move to a cool place, and cool the person with water and fanning.

You can also use HealthLinkBC to check your symptoms.

For more information on preparing for heat and preventing heat-related illness, visit https://climatereadybc.gov.bc.ca/pages/extreme-heat.​​