A heat warning has been issued for Niagara.
Environment Canada says 'extreme heat' is expected for Tuesday through to Wednesday.
Forecasters say a hot airmass approaching the area will bring daytime temperatures in the low thirties over the next couple of days with increasing humidity on Wednesday, humidex values are expected to creep in the mid to high thirties.
Lows between 20 and 22 degrees Celsius are also expected Tuesday night.
Temperatures will cool off Wednesday night as Tropical Depression Cristobal approaches Ontario.