Ottawa rings in September with warm weather, heat expected to stay
Posted Sep 1, 2025 11:23:42 AM.
Last Updated Sep 2, 2025 11:15:59 AM.
While the kids may be back off to school, you may want to hold off on packing away the shorts and t-shirts. Warm weather is expected to remain in the forecast.
To top off the last holiday of the summer, Monday is anticipated to reach a high of 26 C with the humidex making it feel more like 28. Full sun throughout the day is expected with a high UV index.
The first day of school brings a chance of showers and a risk of thunderstorms. The high for Tuesday is 26 C with the humidex making it feel like 27.
Wednesday and Thursday will see a mix of sun and clouds with temperatures remaining in the mid to high 20s before the heat tapers off on Friday.
Normal temperatures for this time of year are a high of 22 C and a low of 12 C.
Fall forecast
Environment Canada released its one to three month projections on Sunday which concludes that Ottawa has a high likelihood of experiencing above seasonal temperatures throughout the fall.
This band of warm weather is expected to stretch through most of central and eastern Ontario.
