The Ontario fall forecast for 2026 is in, and it points to a chillier season than most of the country will see. While much of Canada is expected to enjoy a milder autumn, Ontario stands out as one of the few provinces bracing for below-normal temperatures. There’s also a good chance of snow showing up earlier than usual in some regions.

This outlook comes from the Old Farmer’s Almanac, which released its 2026 national fall forecast with details specific to Ontario. Residents can expect above-average precipitation throughout the season, and that moisture won’t always fall as rain. So, here’s a closer look at what the province should prepare for, week by week.

September: Cool Air, Rain, and a Few Warm Surprises

September is where Ontario’s cooler pattern really kicks in. The average temperature for the month is forecast to sit around 15 C, which is 1 C below normal. That said, the month won’t be uniformly cold. Instead, it will swing between chilly stretches and short bursts of warmth.

From September 1 to 4, conditions will be sunny in the east while the west sees rain. Cool temperatures will settle across the entire province during this stretch. Then, things shift quickly. Between September 5 and 8, thunderstorms roll in alongside a brief return of warmer air.

The cool pattern comes right back afterward. From September 9 to 16, eastern Ontario will see showers while western areas stay mostly sunny. However, temperatures across the province will remain on the cooler side that week. Consequently, residents should keep light jackets handy even on the sunnier days.

Later in the month, the weather becomes more unsettled. From September 17 to 23, showers move through before clearer skies return, though it stays cool overall. Finally, the month wraps up on a damp note. From September 24 to 30, rain and chilly air dominate, closing out September on a noticeably autumnal chill.

October: Snow Showers Arrive in Eastern Ontario

October brings Ontario closer to seasonal norms, with an average temperature forecast of 11 C for the month. Even so, several stretches will feel colder than that number suggests, especially once snow enters the picture. As a result, this is the month where winter starts making its presence known.

The month opens on a dry note. From October 1 to 6, skies stay sunny, but temperatures remain chilly province-wide. That changes quickly, though. Between October 7 and 14, rain moves in and warm air gradually gives way to a colder pattern by the end of that stretch.

Mid-October is when snow officially enters the forecast. From October 15 to 21, eastern Ontario will see rainy periods while the west experiences a mix of rain and snow showers. Temperatures that week are expected to stay chilly throughout. Snow showers are specifically expected in Ottawa and other communities near the Quebec border during this stretch.

The month then closes on a milder, drier note. Between October 22 and 31, eastern Ontario sees warm temperatures with a few scattered showers, while the west enjoys sunny conditions. So, October essentially delivers a preview of winter in its middle weeks before easing back toward comfort by Halloween.

What This Means for Ontario Residents

Overall, this Ontario fall forecast suggests residents should plan for a season that leans colder and wetter than usual. Because above-average precipitation is expected throughout, umbrellas and warm layers will likely get more use than in a typical autumn. Meanwhile, those living near the Quebec border should be especially ready for snow by mid-October.

It’s worth noting that Ontario’s pattern doesn’t match most of the country this year. While other provinces trend milder, Ontario bucks that trend with cooler-than-normal conditions. Therefore, anyone traveling within Canada this fall should check regional forecasts separately rather than assuming the same weather everywhere.

This article’s cover image was used for illustrative purposes only.

Author: Lisa Belmonte, Senior Writer