A warm Halloween for Ontario, Quebec, where October temperature records were broken

A warm puffer jacket has ruined many a Halloween costume in Canada, as chilly late fall temperatures often stand in the way of the perfectly curated look.

But record high temperatures are making many parts of Ontario and Quebec feel more like summer. Toronto, Montreal, Ottawa, London and a number of other cities in the region are expected to hit record highs on October 31.

The warm temperatures stem from a large area of ​​high pressure over the southeastern United States that is bringing much warmer than normal air all the way up to southern Ontario, according to Environment and Climate Change Canada, warning emergency meteorologist Geoff Coulson.

“A lot of people would be forgiven for going outside on a day like today and thinking it was more like late August or early September as opposed to late October,” Coulson said.

That pattern, he says, will end later in the day on October 31. A cold front is expected to sweep through, bringing some rain or even thunderstorms to Ontario.

“These showers and thunderstorms are likely to occur around the time the kids are out trick-or-treating,” Coulson warned.

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Ottawa’s Halloween forecast is 23 C — 1.5 degrees above the record set in 1989. CBC’s Natalia Goodwin spoke with kids and parents about what that means for this year’s trick-or-treating.

Hottest Halloween ever

Toronto is forecast to reach a high of 24 C, the hottest October 31 on record for the city and 13 degrees above average. The day before, Toronto hit a record high of 22C.

Montreal experiences similar conditions, forecast to hit 22 C on October 31 — 12 degrees above average.

The unusual temperatures have also arrived for much of the United States, with higher than normal temperatures from Texas to Michigan and the Northeast. New York City is expected to hit a balmy 25.5 C on October 31, according to the US National Weather Service, about 10 degrees above normal.

Coulson said temperatures will begin to become more seasonable Friday and into the weekend.

2024 could be the warmest year

The temperatures come after a string of record hot months, brought on by climate change and the El Niño weather pattern.

This summer was the warmest on record, according to the Copernicus Climate Change Service, a European Union research institution. August 2024 was 1.51C above pre-industrial levels, while average global temperatures were 1.64C above pre-industrial levels in the 12 months from September 2023 to August 2024, setting off alarm bells for the UN climate conference in Azerbaijan next month.

Copernicus says it is “almost certain” that 2024 will be the warmest year on record.

Environment and Climate Change Canada, meanwhile, examined 37 of the worst heat waves across the country from June to September this year. All were made more likely by anthropogenic climate change.

What is in store for winter

Scientists are now waiting for the La Niña weather pattern, which usually follows an El Niño and brings cooler temperatures to the US and Canada. Coulson said there are signs that La Niña is developing, although it may be a weak one.

“As it develops, the La Niña phenomenon itself tends to affect more the winter months in southern Ontario, and the impacts tend to be more related to precipitation than temperature.”

He added that the long-range weather model suggests that the winter is expected to be slightly warmer than normal in southern Ontario overall.