Heat alert extended

The extreme heat alert has been extended in Toronto as temperatures are expected to hit a scorching 34 C today, feeling more like 40 C with humidity.

This is the fourth day in a row that the city has been under an extreme heat alert.

To make matters worse, the city hasn’t seen substantial rainfall since July 3. There were light showers Friday night but it was “just a sprinkle” — not even enough to measure, according to Tony Cham, a meteorologist at Environment Canada.

Since the start of July, Toronto has seen only 4.4 mm of rain when the norm for this time of the year is about 74.4 mm.

The driest July ever was set in 1957 with 11.4 mm of rain.

Cham says it is hard to predict whether Toronto will break the record this year since there are still nine days left until the end of the month.

But relief may be in sight.

There is a 30 per cent chance of showers Saturday evening and a 60 per cent chance of rain Sunday night into Monday morning.

“There’s still some hope,” Cham said.

Meanwhile, to cope with the extreme heat, the city has opened cooling centres across Toronto and some city pools may extend their operating hours.

Much of the United States and Canada are trapped under a heat “dome” caused by a huge area of high pressure that’s compressing hot, moist air beneath it and keeping the jet stream well to the north.

This high-pressure system is leading to scorching temperatures like the ones Toronto saw Thursday when the mercury hit a sweltering 37.9 C, the highest July day temperature ever recorded at Pearson airport but just shy of the 38.3 C record set on August 25, 1948.

The smog that sometimes accompanies hot weather is nowhere to be seen, though. The city’s only had one smog day this summer. In 2005 — a similar year temperature-wise — there were 20 by this time.

There have been fewer smog days partly because of improved air quality, said Kate Jordan, a spokesperson for the Ontario Ministry of Environment.

In the past eight years, the province has seen reductions in fine particulate matter and nitrogen dioxide — the two main ingredients in smog, Jordan said. But weather also plays a role. “While we’ve had really warm and sunny weather, we haven’t had stagnant air pressure and the hazy conditions,” she said.

This is because the winds blowing through Toronto are not coming from the south, which typically brings in dirtier air and higher humidity, she adds.