After searing heat, Ontario's week goes out with frost risk and snow for some

Digital WritersThe Weather Network
Digital Writers

The 30-degree temperatures of recent days will be very thoroughly in the past as the weekend nears.

The week is set to end very, very differently from how it began, from decidedly summer-like heat, to a blustery, cold rain and daytime highs that could usher in a few snowflakes for high-elevation areas.

Let's take a look back to earlier in the week, when southern Ontario basked in some true summer heat. While temperatures cooled slightly for Victoria Day on Monday, the heat and humidity were quick to return for most of the region by Tuesday – in fact, the city of Toronto tied for their fifth warmest May temperature on record, as daytime highs hit 33.3°C.


That blast of heat was likely the last 30-degree day that the region will see for some time, thanks to a cold front that slashed through the province Wednesday and sent temperatures falling. On Thursday, some parts of the province were almost 10 degrees cooler than on Tuesday.

By Friday, that difference could stretch to 20 degrees, with daytime highs not venturing too far above 10°C for much of the province. The day will feel even more miserable, thanks to a system that's set to bring some rain in through the morning –– along with a nasty surprise for people at higher elevations of the southwest.


"We cannot rule out some flakes mixing in across the higher terrain well northwest of the Greater Toronto Area," says Dr. Doug Gillham, a meteorologist at The Weather Network.

There's also a widespread frost threat Thursday night for northern Ontario, spreading into parts of cottage country by Friday night as well.

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While abundant sunshine returns in time for the weekend, temperatures will still remain several degrees below seasonal on Saturday, more typical of what you'd get during the month of April.

At this point, it looks like the first one to two weeks of June will be near seasonal most days, with a lack of any truly hot weather that's already been felt through May.

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"We'll still have an abundance of pleasant weather for the start of June, but consider this a break from the recent consistent heat," Gillham says, adding that there's no question the 30-degree days will eventually return.

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In addition to the recent heat and humidity, the month of May has featured a severe lack of rain.

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Aside from some quick bursts, which have accompanied isolated thunderstorms, rainfall totals across southern Ontario have been well below seasonal throughout the spring season, with many places reporting near-record dry conditions during May.

A system pushing through on Friday is set to bring between 10-20 mm of rain, providing some much needed moisture to parts of the region. However, areas to the north of the GTA will miss out on seeing any substantial rainfall.

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Be sure to check back for the latest updates on the weather conditions as we head into June across Ontario.