Toronto is stepping into the first day of fall with a blast of summer warmth, as September’s hot streak carries over into the new season.

Environment Canada says Monday will feel more like mid-July, with a forecast high of 25 °C and humidex values closer to 30 °C. Skies will be mostly cloudy with a 60 per cent chance of showers and even the risk of a late-day thunderstorm. Overnight, temperatures are expected to dip only to 17 °C — still well above seasonal norms.

This hot start to autumn caps an unusually warm September, where daytime highs often hovered in the mid-20s, several degrees above the typical 19 °C average. Even nights stayed mild, with lows trending above the seasonal 10 °C mark. While Toronto saw occasional rainfall, much of the month was marked by sunny, dry weather — extending that summer feeling weeks past Labour Day.

Historically, Toronto usually settles into fall-like daytime highs of 20 °C or lower in the final third of September. Data from Environment Canada shows that in most years, the first cool stretch arrives around Sept. 20–22. This year, however, summer has lingered, keeping the city warmer for longer.

Looking ahead, the heat won’t last much longer. Tuesday is expected to reach 23 °C with sun and cloud, before conditions cool slightly on Wednesday with a high of 20 °C. By the end of the week, temperatures are forecast to align more closely with seasonal norms around 19–20 °C, with cooler nights settling into the low teens.

For now, Toronto is holding onto summer — at least for a few more days.