Sunday sets records for heat, humidity in southern Ontario as ridge settles in
The extreme heat has already seen some cities beat their all-time heat records, with soaring temperatures and humidity settling in for a few days this week. Take action to protect yourself and others, as extreme heat can affect everyone’s health
Southern Ontario has been enduring a multi-day stretch of extreme heat and humidity beginning Sunday, with temperatures climbing into the low- to mid-30s and humidex values rising toward the mid-40s.
In fact, heat alerts stretch from Denver, Colo., and New Orleans, La., to Ottawa, Ont., as hazardous heat and humidity lock into place heading into the final full week of June. Heat warnings were recently expanded to include parts of northern and eastern Ontario.
Going into Monday, Ontario can expect to see a similar level of high temperatures and humidex numbers, with heat warnings still in effect till Tuesday.
DON’T MISS: What is a mesoscale convective system? How an 'MCS' can spell danger
The thunderstorm risk will move north and east on Sunday, thanks to a heat ridge in place, but a greater chance will return to southern Ontario on Tuesday. However, there is still some uncertainty on the timing of the cold front on Tuesday and the storm threat.
Northern Ontario storm risk to continue into Monday
A powerful ridge of high pressure that developed over the eastern United States has settled over northern Ontario.
The outer periphery of these heat ridges serve as the ideal environment for the development of thunderstorms, which then ride around the edge of the ridge like trains on railroad tracks.
Storms are expected to continue across northern Ontario into early morning Monday, with potential for some to turn severe.
The focus going into Monday will be the severe weather will be in northern Ontario, though, where strong wind gusts, large hail, heavy rain, and even some rotating storms are possible.
The active weather remains north along the ridge, so not much rain is in the forecast for southern Ontario as we head into Monday.
We are tracking a cold front that is expected to sweep through on Tuesday. It will likely bring the risk of thunderstorms across southern Ontario before the cold front passes through Tuesday evening.
WATCH: How long will the heat in southern Ontario stick around?
Two cities break heat records with warning still in effect
We’ve already seen temperatures and humidity increase to dangerously high levels as the ridge of high pressure intensified Sunday.
At its highest, Toronto broke its record humidity for June, jumping to 46.3, 0.7 points higher than its former all-time peak on June 30th, 2018.
It was the same with Hamilton, which saw the humidex jump by 2.3 points higher than its peak humidity in June of 2018, reaching a high of 46.6
Toronto and Hamilton weren’t the only ones heating up; Burlington had a high of 34° with a humidex of 44. Sarnia was sitting at 33.9° with it feeling like 46, and Peterborough had the biggest gap, with temperatures at 31.7° while it felt like 45.
This level of heat is only going to continue into Monday, with a focus on the extreme heat and humidity, while heat warnings are spread across a wide swath of Ontario.
We’re expecting at least three days of temperatures of 33°C or higher across most of the GTA and southwest—with daytime humidex values continuing in the mid-40s.
Overnight lows will remain in the mid-20s, providing little relief for those living without reliable access to air conditioning.
If we see three or more consecutive days of 33°C or higher at Pearson airport, it will have been 13 years (since 2012) since we experienced a stretch of heat like this in June.
Record-breaking or not, this is an impressive heat wave that needs to be taken seriously.
Hot weather safety tips
Drink plenty of water. Avoid caffeine and alcohol, which can be dehydrating.
Avoid direct sunlight, especially during peak hours and when the UV rating is high.
Wear lightweight, loose-fitting clothing.
Use air conditioning when possible. If you do not have access to air conditioning, consider visiting a cooling centre, a shopping centre, or a public library.
Check on elderly relatives and other vulnerable neighbors.
Avoid strenuous activities during the hottest parts of the day.
If you experience symptoms of heat-related illnesses like dizziness, nausea, or confusion, seek medical attention.
Stay with The Weather Network for all the latest on conditions across Ontario.