File photo courtesy of © Can Stock Photo / Kzenon

Heat records could fall Friday

Decades-old heat records could be shattered across southwestern Ontario Friday as temperatures are expected to soar to their hottest level so far this year.

Environment Canada expects daytime highs on Friday to climb 34 C in London, and 37 C in Chatham-Kent and Windsor Essex. But because of the humidity, it will feel more like the mid-40s throughout the region. If temperatures reach those values, they would smash records set more than 70 years ago when the daytime high hit 33.9 C in London and 36.7 C in Windsor on July 19, 1946.

“[We’re] anticipating issuing a heat warning for the southwest on Thursday afternoon and that heat warning would be in effect for Friday and in through the weekend,” said Environment Canada Meteorologist Geoff Coulson. “At this point in time we will be getting close to the criteria during the day on Thursday, but then surpassing the heat warning criteria for Friday and into the weekend.”

Windsor-Essex and Chatham-Kent have been under a heat warning since earlier this week, while London-Middlesex has remained just under the threshold for one. Severe thunderstorm watches and warnings could also be issued as the scorching temperatures could lead to the development of severe storms that pack heavy rain, hail, and damaging winds.

Normal daytime highs and lows for this time of year are around 26 C and 15 C.

According to Coulson, a hot, humid air mass worked its way up from the deep south and has been sitting over much of the province for the last couple of days. As we head into the weekend it will “reinforce” itself to the point where there will even be little relief from the heat during the overnight hours.

“For Friday night into Saturday morning and Saturday night into Sunday morning temperatures are expected to stay in the low 20s, with the humidity still making it feel like the high 20s to low 30s,” said Coulson. “One of the concerns in these events is that people without air conditioning don’t really get a break in those overnight hours.”

An extended heat warning has been issued by the Windsor-Essex County Health Unit and the Chatham-Kent Public Health Unit. The Middlesex London Health Unit has yet to issue a heat alert due to this system.

The health unit issues heat alerts when Environment Canada forecasts daytime highs of 31 C or higher for one day or more and when humidex values reach 40 C or higher for at least 24 hours.

Heat warnings and extended heat warnings are issued by public health officials when sweltering weather sticks around for two or more days in a row.

In order to avoid any heat-related illnesses, Coulson recommends people limit their time outdoors.

“The best thing to do is try to minimize your most strenuous activity during the heat of the day between 11 a.m. and 3 and 4 p.m., staying hydrated is very important so drinking plenty of water,” said Coulson. “Sun safety at this time of year also very important. So using the sunscreen, wearing the floppy hat to protect the ears and the back of the neck. It is as simple as if you don’t need to be outside or if you can get a lot of breaks in air conditioning, that is recommended.”

The sweltering weather will ease slightly on Monday as a cooler, less humid air mass arrives as a weak cold front passes through the region.