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Tricky, tumultuous weather will trouble Ontario this long weekend

Thursday, May 19th 2022, 9:05 pm - Your weather icons show clouds and thunderstorms for the long weekend across southern Ontario, but will it be a washout?

It’s going to be a tumultuous long weekend across Ontario as an active pattern brings an annoying mix of seasons to the province. If you’re planning a getaway this weekend, you’ll have a tough time packing for the heat in some areas and the chill in others, not to mention dodging the risk for severe storms in spots.

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The weekend will start off on a sultry note with very warm temperatures and a dollop of unusually summery humidity bathing the region. This muggy airmass will set the stage for thunderstorms and torrential downpours.

However, before you know it, a cold front careening across Ontario will reverse our temperatures and make things feel more like April by the end of the weekend. Take a look below at how your forecast will fare each day this weekend.


Friday will see the heat and humidity build into southern Ontario and across cottage country, with widespread humidex values in the low to mid 30s, possibly even reaching the upper 30s for sections of the southwest.

Friday Humidex

If you glance at The Weather Network app, however, you could see a misleading rain icon for the region, as a system tracks into the Great Lakes and the warm front lifts north through southern Ontario.

Friday Storms

We’ll see a risk for thunderstorms across much of southern Ontario during the day on Friday. The greatest risk will exist in southwestern Ontario and toward Lake Huron and Georgian Bay as a cold front pushes into the region. Isolated thunderstorms are possible closer to the Greater Toronto Area.

A line of strong to severe thunderstorms are forecast to develop along this front late day and into the evening hours. The biggest threats with storms that do develop will be large hail and gusty winds.


The cold front will continue its march through southern Ontario Saturday, leaving the Huron Shores and northern cottage country with temperatures in the upper teens and low 20s.

Saturday Humidex

The heat and humidity will still remain widespread across the Greater Toronto Area, eastern Ontario and the lower Great Lakes, with humidex values in the low to mid 30s for one more day.

Saturday’s storm threat will target the Highway 401 corridor from Windsor through Ontario, continuing on into eastern Ontario and southern Quebec. Widespread thunderstorms are likely to bubble up as the cold front presses into the warm and unstable air.

Saturday Storms

Some of Saturday’s storms could reach severe levels, with large hail and damaging wind gusts posing the main risk. Pay close attention to the weather through the day and make sure you have a way to receive severe weather warnings the moment they’re issued.

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Unfortunately, an unsettled boundary will remain over southern regions into the day on Sunday, drawing up a second system and bringing showers and a slight risk of thunderstorms back to eastern Ontario.

image - 2022-05-19T075302.309

The timing of the system is still up in the air. If this second system moves faster, we’ll see drier conditions for the second half of the day on Sunday.

Temperatures will be much cooler in the north towards the Huron Shores and cottage country, with daytime highs in the low to mid double digits. The 401 Corridor will likely hang on to the low 20s for one more day.



Monday will be the driest day of the long weekend, but it comes at a price.

All of the weekend’s heat and humidity will have been swept away by the cold front, leaving behind temperatures that are 2-5°C below seasonal for late May. Widespread daytime highs in the low to mid teens are in the forecast.

Monday Icons

Cooler-than-seasonal temperatures will persist through the middle of next week, with changeable temperatures and an unsettled pattern taking shape for the final week of May.

Be sure to check back for the latest updates on your long weekend weather across Ontario.

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