Unusually warm weather is delaying arrival of Ontario's fall colours

An unseasonally warm stretch of summer-like weather is delaying the vibrant display of fall colours across Toronto and most of southern Ontario this fall, with the majority of leaves still ranging between yellow and green.

While September is practically almost over, zero fall storms have touched down in Toronto so far, and not a drop of rainfall is on the horizon in the city for at least another week.

According to The Weather Network, a sprawling ridge of high pressure over Hudson Bay has acted as a weather shield, which has kept all the rainfall south of Toronto.

While some areas outside of the city, including Hamilton and Burlington, did see a few showers on Monday, Toronto stayed warm and dry, with long-range models showing that it will be another seven to 10 days before we see any rainfall at all.

Long live summer!🌞https://t.co/OhSTPiL4un #Toronto #OntarioWeather

— blogTO (@blogTO) September 22, 2023

In fact, the city recorded its last measurable rainfall over two weeks ago on September 12, and if the dry weather continues, Toronto could possibly break its record for the longest streak of dry weather in September.

According to Ontario Parks’ Fall Colour Report, many areas and hiking trails in southern Ontario continue to see mostly green or yellow leaves, with only 10 to 20% of leaves having changed colour in the Toronto area.

As fall approaches, temperatures typically drop, and the days get shorter, meaning trees receive less direct sunlight and the chlorophyll in leaves breaks down, revealing yellow and orange pigments.

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Dry conditions in the early fall can also trigger an “early shutdown” of trees in preparation for winter, causing leaves to drop from trees early without reaching their full-colour potential, according to the Toronto and Region Conservation Authority (TRCA).

While temperatures have remained warm for now, Ontario is still expected to see a “fickle fall” and “harsh push” of cold weather sometime in October, with more mild temperatures taking over as we head into winter.