Those who have this Simcoe Day off can look forward to a hot one: the City of Toronto has issued a heat alert today.
Temperatures will climb to 33 C today, but will feel more like 37 C. There’s also a piping UV index of 9, or very high, according to Environment Canada.
Toronto Public Health staff monitors its heat health alert system to determine whether a heat alert should be issued . The system compares forecast data to historical weather conditions which have led to increased mortality in Toronto in the past.
Factors taken into consideration include conditions like temperature, dew point, humidity, cloud cover, wind speed and direction.
This is the city’s sixth heat alert of 2011. July was the hottest July on record for the City of Toronto with an average temperature of 24.37, according to Dave Phillips, a climatologist with Environment Canada. That beat out the previous record of 24.3 in 1999.
And the warmest day the city has ever seen was this past July 21, when the mercury rose to 37.9 C. The average temperature for the day was 32 C, which beat out a previous record of 31.5 C on Aug. 1, 2006.
“If you stuck a thermometer in Toronto this past July, it would say well done,” Phillips said.
The warmest temperature ever recorded at Pearson was 98.3 on Aug. 25, 1948.
At the rate we’re going, this summer may beat out the summer of 1955 as the hottest Toronto has ever seen. August is expected to mirror the record-setting July we just had, which was not only the hottest July, but also hotter than any June of August the city has ever seen, according to Phillips.
The average temperature for July and August combined in 1955 was 23.6 C. “We are now at 24.4 C, so we could be a degree cooler in August and still break that record,” he said.
July was certainly one for the books in more ways than one. There were 16 days where the average temperature hit above 30 C, and we usually only have 6. We had 30 hours more of sunshine than average, and we only received 43 per cent of what we’d normally get in terms of precipitation—we had 32.4 mm of rain, when we normally have an average of 74.4. July dragged us through a 14 day dry spell as well.
“It was a scorcher. Toronto was well done, baked, grilled roasted.
“It was the hottest day ever, it was the hottest month ever, I mean, you run out of superlatives talking about this particular month.”
In recent memory, the hottest summer Toronto has seen was 2005. The average temperature for July that year was 24.1. That year also had a number of smog days, with 12.5 in July alone. Phillips said there were probably more than 30 smog days throughout the duration of that summer.
In 2005, there were 10 nights on which the temperature remained above 20 C, compared with the 12 we had last month, which brings us to a trend Phillips said is gaining momentum.
“What’s really different in Toronto these days is the warm nights. It’s a hot time in the old city.”
He chalks the sultry summer nights up to increased urban development.
“The city is just getting warmer and cloudier, there’s more heat being trapped in.”
In terms of heat this holiday Monday, Phillips said we shouldn’t rule out the possibility of a humidex advisory being issued. Right now the humidex sits at 37 C, and advisories are issued when it hits 40 C.
The city is urging people to drink lots of water, go to air conditioned spaces and try to stay out of the sun.
In stark contrast to the sweat bath we’re in now, the lowest average temperature for a Toronto summer on record is 17.7 C, and that was in 1965.
— Sarah Ratchford, Staff Reporter