Toasty weekend warmth in Ontario may bring a thunder risk

We’re trading the wind chill for the humidex across Ontario this weekend as the season’s warmest air floods into the province.

Temperatures rising into the weekend could push the feels-like value close to 30 for communities in the far southwest.

This warmth will come at a cost. Keep the umbrella handy heading into next week as showers and possibly even some thunderstorms arrive with the rising temperatures.

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Friday morning frost, temperatures tick up Saturday

We’ve got one more chilly morning to get through before the real warmup arrives.

A frost advisory is in effect through early Friday morning for the City of Toronto, portions of the Niagara Peninsula, and far southwestern Ontario as morning temperatures dip close to the freezing mark.

Friday morning’s chill will be a distant memory by this weekend. Multiple systems will trek across the western Great Lakes beginning on Saturday. This storm track will allow southerly winds to spill warm and humid air across the border into southern Ontario.

Rain will build into the region beginning Saturday as mild temperatures inch into extreme southwestern Ontario.

Readings soar on Sunday

Sunday could be the warmest day of the year for much of southern Ontario as this May-like pattern arrives to end the weekend in style.

The warmest readings we’ve seen so far this year include:

• 26.1°C in Windsor on April 14

• 23.8°C in Hamilton on April 9

• 20.6°C in Toronto on March 13

• 19.9°C in London on April 14

Daytime highs on Sunday will soar into the mid-20s for many communities, with humidex values possibly cracking 30 in the southwest.

Given the warmth in the forecast, Toronto, Hamilton, and London are on track to beat 2024’s high-mercury mark by Sunday, while Windsor might fall short by just a hair.

Warm, moist winds in the middle of spring is a recipe for possible thunderstorms. While the most favourable conditions for storms will remain stateside, we may have to dodge a few pop-up storms across southern Ontario on Sunday. Stay tuned over the next few days for specifics on that potential.

Warmth sticks around into early next week

Another system tracking into northern Ontario on Monday will keep the unseasonably warm air parked over the southern half of the province to start the week.

Afternoon temperatures will crack the 20-degree mark for much of southern Ontario, with slightly cooler readings possible around the Golden Horseshoe as the lake cools things off a bit.

We’ll see additional showers and possibly a risk for rumbles of thunder as that disturbance passes the region to the west.

Temperatures will likely start to moderate back toward seasonal as we head into the second half of the upcoming week. Warm-weather lovers may not have to wait long for above-seasonal conditions to return, as more unseasonable warmth could arrive in time for the beginning of May.

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

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