Muggy thunderstorm threat builds across southern Ontario, Quebec

We’re firmly in storm season across the eastern half of the country as teases of summer begin working north of the border.

A warm, humid air mass parked over Ontario this week will send temperatures into the upper 20s, with plenty of towns pushing the 30-degree mark for the first time this season. Humidex values ​​will push well into the 30s, especially across the southwest and away from the lakes.

DON’T MISS: Stuck in your car during a tornado? Here’s what you should do

All that instability needs is a trigger to kick off showers and thunderstorms. We’ll have plenty of sparks over the next couple of days to get scattered storms going with the heat of the day.

Ontario atmospheric moisture Tuesday_May 20

The thunderstorm risk will also extend into southern Quebec, along with the muggy air.

Below is a break down of what to expect over the coming days.

Storms expected to develop on Tuesday

Tuesday will see another round of thunderstorms develop with the heat of the day across southern Ontario as a low pressure system tracks storms north and east of the Greater Toronto Area (GTA) through Tuesday afternoon. These storms could produce torrential rains and localized flooding to some areas.

southern Ontario Quebec Tuesday thunderstorm risk map May 21 2024

There is a chance some of the storms could reach severe criteria in parts of cottage country and across eastern Ontario. These areas could see large hail, strong winds up to 90 km/h, and heavy downpours, given the amount of moisture storms will be able to tap into.

Another warm front lifting north across the GTA on Tuesday night could serve as the trigger for an additional round of nocturnal thunder over the region. Storms may move through the Montreal area and Eastern Townships overnight Tuesday, but will diminish in severity as nighttime temperatures set in.

southern Ontario Quebec Tuesday noon precipitation forecast May 21 2024

Remember, though, that even a non-severe thunderstorm is still dangerous. Lightning is the greatest threat posed by any thunderstorm. Stay close to safe shelter if you’re planning to spend time outdoors. If you’re close enough to hear thunder, you’re close enough to be struck by lightning.

Wednesday sees greater potential for severe storms

Temperatures in the upper 20s with high humidex values, in conjunction with a cold-front moving in from the states and low pressure over Lake Superior, will support the risk for strong and severe thunderstorms across southern Ontario and Quebec on Wednesday.

Southern Ontario Wednesday humidex May 21 2024

MUST SEE: How severe weather alerts are issued, and potentially save lives

The timing of the cold front’s passage, as well as lingering storm activity from Tuesday, will dictate the severe thunderstorm potential across the region. At this time, however, the severe potential is fairly widespread throughout southern Ontario and Quebec.

The main threats from these storms will be large hail, heavy rainfall, and strong wind gusts. Folks could be seeing these thundery conditions last into the evening hours on Wednesday.

southern Ontario Quebec Wednesday thunderstorm risk May 21 2024

As storms roll in off Georgian Bay on Wednesday afternoon, there is a chance folks in and east of cottage country could see a tornado. Rest assured, though, as forecasters are keeping a close eye on this risk throughout the day.

It’s always a good idea to have a safety plan in place for severe weather. Make sure you have a way to receive severe weather warnings the moment they’re issued, especially at night.

Temperatures and humidity levels will both tumble behind the cold front, allowing more seasonable air to spill over the region heading into the end of the week.

Stay with The Weather Network for all the latest on your forecast across Ontario and Quebec.

WATCH: These are the dangers you face during a lightning storm

Click here to view the video