Niagara is under an Environment Canada heat warning as hot and humid conditions are expected to last until tomorrow.
Daytime temperatures are expected to reach the mid-30s, but feel more like the low-40s with the humidity.
There won't be much relief at night either with overnight lows settling in the low- to mid-20s.
A cold front is expected to move through the region Tuesday night with rain and thunderstorms.
Environment Canada meteorologists expect the air quality to deteriorate during the hot and humid spell, which may cause the Air Quality Index to approach the high risk category.
Signs of heat related illness can include swelling, heat exhaustion, and cramps.