Autumn to start with storms, long stretch of humidity
Posted Sep 22, 2025 07:51:09 AM.
Last Updated Sep 22, 2025 10:07:38 AM.
Despite the summer-like feeling in the air, autumn begins Monday at 2:19 p.m.
A high of 24°C Monday with humidex values around 29 will be the new norm to start the new season.
570 NewsRadio Meterologist Carl Lam explains.
“Temperatures are going to be running above average as we go through the week and into the weekend too,” he said.
“Temperatures are generally going to be in the low twenties, but you factor in the humidity it will feel like the mid to upper-twenties. It looks like by the end of the month we will start to clear some of the humidity out, but there is a long stretch between now and then.”
That humidity could bring some storm activity.
Sunday night, the last night of summer, saw some big rain and thunderstorms move into Waterloo Region.
Early data from Environment Canada shows about 39 mm of rain fell. A severe thunderstorm warning was briefly in place as well.
At one point during the storm, the Highway 8 Eastbound ramps by Fairway Road were closed due to flooding.
Lam said he expects those storms to return as fall begins.
“Once we go into the afternoon during the heat of the day, that’s where we could have some of those thunderstorms firing up with those heavier downpours too, and then that could even extend into the evening before things start to taper off.”
The warm start to autumn follows a September that delivered extended stretches of summer-like weather.
Daytime highs frequently reached the mid-20s, with several days climbing above the seasonal norm of 19°C.
Overnight lows also trended warmer than the historical average of 10°C, keeping conditions mild well into the evenings.
With files from Lucas Casaletto
