It's October! Are 30° days finally behind us, Ontario?

When will sweater weather finally make its way across all of Ontario?

When you think of fall, you probably think of October. October brings a perfect blend of crisp, chilly air and daytime warmth, commonly known as 'sweater weather.'

While parts of Ontario have already gotten a taste of classic fall, southern Ontario has remained stuck in summer throughout September.

Now that it's October, have we finally seen the last of summer's 30°C heat? Unfortunately, not quite yet...

SEE ALSO: Canada's October wildcard: Record warmth on the table, but snow still in play

Summer heat sticks across southern Ontario into October

High pressure over the province will help to extend summer's heat across southern Ontario into the first full week of October.

Ontario upper level ridge beginning of October - Oct. 1, 2025

The heat will even creep into northeastern Ontario, where we will see temperatures hover 8-12 degrees above seasonal, whereas they'll be about 5-8 degrees above seasonal across southern Ontario.

By Saturday, we'll see the high pressure shift east, but the clockwise flow of air will pull in warmer temperatures from the southern United States.

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DON'T MISS: Canada ends September with its first -20°C reading of the season

We'll see plenty of sunshine, and daytime temperatures will soar into the mid- to high 20s heading into next week. Southwestern Ontario could even see the thermometer reach the dreaded 30-degree mark.

Ontario Tuesday forecast temperatures and departures - Oct. 1, 2025

Without the cool air and rainy days we know and love about fall, we will see drought conditions continue to get worse over the coming days.

This isn't the first time we've had summer heat linger well into fall, however. Some cities across southern Ontario have had to wait a full week into October for the temperature to finally drop.

Latest 30-degree days in southern Ontario:

  • Windsor: October 8, 2007 (31.9°C)

  • Toronto: October 8, 2007 (31.6°C)

  • Hamilton: October 8, 2007 (30.3°C)

  • London: October 6, 1946 (30.0°C)

WATCH: Can Canada expect snow in October? Find out in our monthly weather outlook, below

Stay with The Weather Network for more information and updates on your weather across Ontario.