The Middlesex-London Health Unit is reminding Londoners to stay cool as the region enters a heatwave.
The heat warning begun Sunday and will likely last until Wednesday, health officials say.
The early September heatwave comes as upcoming daytime highs are set to reach 31 C to 35 C, with the hottest days expected to be Tuesday and Wednesday.
The health unit says people should stay safe and hydrated, drink plenty of water, and avoid too much time outdoors.
The daytime high is set to drop on Thursday, with a high of 24 C.