Multi-day heat event ongoing in London and surrounding areas

Julie Atchison has the latest forecast for Aug. 11, 2025

The multi-day heat event continues for most of Ontario on Monday, including London and surrounding areas.

Under a heat warning, daytime highs are expected to be anywhere from 32 to 35 C with the humidex making it feel like upwards of 42 C.

According to Environment Canada, the heat will continue through Tuesday or possibly Wednesday for some areas as a cooler air mass is expected to arrive Tuesday night.

Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high risk category.

Here’s a look at the rest of the forecast

Monday: Mainly sunny. Fog patches dissipating this morning. Wind becoming south 20 km/h late this morning. High 33. Humidex 40. UV index 8 or very high.

Monday Night: A few clouds. Wind south 20 km/h becoming light this evening. Low 21.

Tuesday: Mainly cloudy. 40 per cent chance of showers in the afternoon with risk of a thunderstorm. Wind becoming southwest 20 km/h gusting to 40 late in the morning. High 32. Humidex 39. UV index 8 or very high.

Wednesday: A mix of sun and cloud with 40 per cent chance of showers. High 30.

Thursday: Sunny. High 28.

Friday: Sunny. High 29.