ONTARIO — Autumn officially arrives in Ontario today, Sept. 22, bringing shorter days, cooler nights and the beginning of what forecasters say could be a longer, milder and particularly colourful fall season.
The autumnal equinox occurs Tuesday evening, marking the astronomical beginning of fall in the Northern Hemisphere. The equinox happens when the sun crosses the Earth’s equator from north to south, beginning the seasonal journey toward the shortest day of the year at the winter solstice in December.
While meteorologists consider Sept. 1 the beginning of meteorological fall, the equinox traditionally marks the start of astronomical autumn.
The seasonal change is already becoming noticeable across Ontario. Frost advisories have appeared in parts of the province as overnight temperatures decline, while daylight hours will continue getting shorter until the winter solstice on Dec. 21.
Despite the cooler nights, Ontario may not have to rush into winter.
Weather forecasters are anticipating an extended and generally milder fall across much of southern Ontario, influenced in part by a strong El Niño pattern in the Pacific. Temperatures through much of the season are expected to remain warmer than average, potentially delaying the arrival of persistent winter conditions until later in the year.
The Old Farmer’s Almanac is also forecasting a relatively mild October, although periods of unsettled weather and even the possibility of some mid-month snow showers remain in the longer-range outlook.
For many Ontarians, however, the biggest attraction of autumn will be the changing leaves — and 2026 could produce an impressive display.
Ontario arborist Erik Benneter says the province’s wetter summer could contribute to brighter fall foliage because trees have experienced less drought stress than during some previous seasons.
The additional rainfall could also delay the colour change slightly compared with last year, potentially producing a later but more vibrant display of red, orange, burgundy and gold across the province.
Northern Ontario typically sees autumn colours first, followed progressively by central and southern regions as daylight hours shorten and temperatures fall.
Across much of Ontario, the prime viewing period generally runs from mid-September through mid-October. In the Toronto and Greater Toronto Area, noticeable colour changes normally begin around late September and continue into October.
Muskoka is expecting early colour viewing from approximately Sept. 20 through Oct. 3, with peak maple colours anticipated around Oct. 4 to 8. A second period dominated by golden foliage is expected to continue into mid-October.
Actual timing can vary considerably depending on local rainfall, sunshine, nighttime temperatures and the health and location of individual trees. Urban trees can also experience different conditions because of local microclimates.
Ontarians planning fall drives and day trips can follow changing conditions through the Ontario Parks Fall Colour Report and regional trackers covering destinations such as Algonquin Provincial Park and Muskoka.
Another familiar autumn sight will arrive shortly after the equinox. The Harvest Moon — traditionally the full moon occurring closest to the autumnal equinox — arrives later this month.
The clocks will also change later in the season. Daylight saving time ends Sunday, Nov. 1, when clocks move back one hour and Ontario returns to standard time.
Halloween attractions are also beginning to open across the province. Seasonal stores are operating at numerous Ontario locations, while major fall attractions such as Pumpkins After Dark are preparing events in Milton, London and Markham.
So while Sept. 22 officially opens the door to autumn, Ontario’s 2026 fall may unfold more gradually than usual — offering residents additional time to enjoy comfortable temperatures, scenic drives and what could be one of the season’s more colourful displays.