Northeastern New Brunswick is now under a heat warning, according to Environment Canada.
The federal agency has issued the warning for the Acadian Peninsula, Bathurst and Miramichi areas.
Temperatures are expected to reach the mid-30s C on Monday and Tuesday.
WATCH: Moncton shelter kept busy during heat wave
However, a hot and humid air mass will cause humidex values to reach 38 C.
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Environment Canada is recommending that New Brunswickers drink plenty of water and stay in a cool place.
Cooler conditions are expected on Wednesday.