Toronto and the rest of the Golden Horseshoe will be enveloped in sweltering heat and humidity for the next few days, with daytime temperatures climbing above 30 degrees C and humidex values nearing 40.

In its advisory, Environment And Climate Change Canada (ECCC) said a heat event is expected to begin on Sunday and may continue into Tuesday.

“A hot and humid airmass will reach southern Ontario Sunday. Daytime maximum temperatures are expected to be 29 to 31 degrees Celsius with humidex values near 40,” the advisory read.

“There will be little relief at night as minimum temperatures are expected to be near 20 degrees Celsius.”

The federal agency noted that the hot and humid air can also deteriorate air quality, resulting in the Air Quality Health Index approaching the high risk category.

Toronto will see sunny conditions in the morning on Sunday before clouds roll in the afternoon with a 40 per cent chance of showers.

ECCC said there is also a risk of thunderstorms late Sunday afternoon. The high will be 30 C with a humidex value of 38. The low will be 21 C.

On Monday, the temperature will reach a high of 31 C, with the forecast calling for a mix of sun and clouds and 40 per cent showers during the day.

It will be mainly cloudy on Tuesday with a 40 per cent chance of showers and a high of 29 C.