Coming temperatures in the 30s prompt heat warning for Ottawa

A heat warning is in effect for Ottawa as temperatures are expected to soar to midsummer highs over the next several days.

Environment Canada's forecast for the capital includes highs of 30 to 33 C this coming week, after a cooler than average August that saw no days above 29 C for the first time in more than a decade.

Humidex values in the next week could reach as high as 40, Environment Canada warns.

"A hot airmass is expected to affect the area beginning Sunday and persisting into Wednesday. Despite overnight temperatures being lower than warning criteria in some areas, humidex and daytime highs will be very atypical of early September," the warning states.

Sunday's forecast is sunny with a high of 30 C and a humidex of 37. Labour Day Monday could see a high of 31 C and the temperature could hit a high of 33 C on Tuesday, when tens of thousands of Ottawa students head back to school.

The warning also comes as city beaches are no longer supervised by lifeguards.

Overnight lows could be between 16 and 21 C over the next several days.

Environment Canada says the passage of a cold front will bring an end to the heat on Wednesday. Thursday's forecast high is 29 C.