Heat warning continues in London, Ont., but cooldown coming

The Myles family plays on the swings at Basil Grover Park in London, Ont.on Monday May 18, 2026 (Brent Lale/CTV News London)

The yellow heat warning issued by Environment Canada continues in the London area, but relief is on the way.

The first heat event of the season begins Monday afternoon and is expected to continue into Tuesday.

Daytime highs near 30 degrees Celsius. Humidex values near 36. Overnight lows of 18 to 20 degrees Celsius.

Here’s the extended forecast:

Tuesday:

• Mainly sunny early, with increasing cloudiness in the afternoon. A few showers are expected, with a risk of a thunderstorm. Wind will become southwest at 40 km/h, gusting to 60 km/h late in the morning. High 31C. Humidex 35. UV index 9 (very high).
• Cloudy with a 60 percent chance of showers or thunderstorms. Low 11C.

Wednesday, May 20:

• A mix of sun and cloud with a 30 percent chance of showers. High 17C.
• Clear. Low plus 4C.

Thursday, May 21:

• Sunny. High 17C.
• Cloudy periods. Low 7C.

Friday, May 22:

• Cloudy. High 17C.
• Cloudy with a 40 percent chance of showers. Low 12C.

Saturday, May 23:

• Cloudy with a 40 percent chance of showers. High 18C.
• Cloudy. Low 13C.

Sunday, May 24:

• Cloudy with a 60 percent chance of showers. High 18C.