A heat warning has been issued by Environment Canada covering London-Middlesex and most of Southern Ontario ahead of a “heat episode” on Thursday and Friday that will bring daytime highs in the low thirties with humidex values in the mid-to-upper thirties.
In an advisory issued Wednesday afternoon, the national weather agency said the region will also see overnight lows around 20 degrees. Things will start to cool off Friday night with the arrival of a cold front, the advisory said.
“It is just going to be a two-day event, we are anticipating a cold front will sweep through the area on Friday, that’s going to kick off some shower and thunderstorm activity,” said Geoff Coulson, Warning Preparedness Meteorologist with Environment Canada.
“In the wake of that cold front for the weekend, we’re looking at a much less humid brand of air, also temperatures not as hot, so daytime highs on both Saturday and Sunday (are a) more seasonal 25 degrees Celsius, and again with much more comfortable levels of humidity.”
London is forecast to see sunny conditions on Thursday with an afternoon high of 31 degrees, feeling more like 38. On Friday, Environment Canada is calling for cloudy conditions, a 60 percent chance of showers or thunderstorms, and a high of 32 degrees. Over the weekend, both Saturday and Sunday are sunny with highs of 25 degrees.
“Even with these warmer temperatures and some of the heat events we’ve had through the summer so far, temperature-wise we’re really not that much warmer than normal,” Coulson said.
“I think it does feel that way, because the two previous summers we didn’t really see as much in the way of heat and humidity as we’ve seen so far this summer.”
Coulson says Environment Canada is advising residents keep in the shade or stay indoors between the hours of 11 a.m. and 4 p.m.
“If you have to be outside, especially for those that have to work in these conditions, it’s obviously a good idea to take frequent breaks, to rest and also to replenish your fluids by drinking plenty of water or sports drinks.”
As for any potential relief from the heat, Coulson says the long-term forecast is showing warmer than average temperatures similar to July.
“We are looking at more seasonal temperatures for the weekend and into the first part of next week, but there are already some indications that we could see more in the way of hot, humid weather starting to develop again by the middle of next week,” Coulson said.