Montreal heat wave

Wednesday will be hot and humid. Humidex values will reach 40 or more.

Heat warnings are issued when very high temperature or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.

Environment and Climate Change Canada are warning people to limit physical activity, saying: "Very hot temperatures or humid conditions are expected to present an increased risk of heat illness such as heat stroke or heat exhaustion."

Temperatures Wednesday night will be in the mid-20s, making for a sleepless night.

Daily highs on Tuesday will be in the low 30s in southern Ontario, where a heat warning is in effect.