Dangerous heat and humidity build from Toronto to St. John's
Temperatures in the middle to upper 30s will combine with high humidity to lead to dangerous conditions for the next several days. Excess moisture in the atmosphere will keep nights muggy, preventing any meaningful relief from the heat of the day.
Humid heat affects everyone. Sensitive groups are especially vulnerable to heat-related illnesses, but even healthy folks are susceptible to heat exhaustion or worse in extreme heat.
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Temperatures stay hot into this upcoming week
Widespread heat warnings are in effect from Ontario through Newfoundland. This includes cities such as Toronto, Ottawa, Montreal, Quebec City, Fredericton, Charlottetown, Gander, and St. John's.
A strong ridge of high pressure parking over Eastern Canada will lead to numerous days of high heat combined with excessive humidity, which could lead to feels-like values in the upper 30s to around 40 at times.
Multiple cities—including Toronto, Ottawa, and Montreal—are in the midst of a four- to five-day stretch of daytime highs at or above 30°C.
Saturday marked the third day this year we've seen a high temperature at or above 30°C in St. John's, making for the highest number of 30-degree days ever recorded in a single year.
This Saturday also featured Toronto's nineteenth day at or above 30°C so far this season, pushing the city past its average of 17 such days per year.
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The extreme heat and lack of precipitation has allowed conditions to reach 'very high' to 'extreme' fire danger across much of Atlantic Canada. Widespread burn bans are in effect across all four provinces.
Why humid heat is dangerous
Sweat cools us off by wicking heat away from our skin as it evaporates. Humidity prevents our sweat from evaporating efficiently—the trapped heat causing our body temperature to rise. This can lead to heat-related illnesses such as heat exhaustion and heat stroke.
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Humidity also prevents nighttime lows from cooling off as much as normal, providing little to no relief from extreme daytime temperatures.
Day after day of high heat and humidity take a toll on those living without air conditioning, folks who have chronic illnesses, and the elderly.
Seek out air conditioning as much as possible, stick to the shade, stay well hydrated, and frequently check in with your vulnerable friends, family, and neighbours.
Header image created using graphics and imagery from Canva.
WATCH: Five tips to keep in mind during a heat wave
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