A special weather statement is in effect for Kapuskasing, Smooth Rock Falls and Hearst.
Environment Canada says the first heat event of the season is expected today.
The weather agency says mainly sunny skies are expected along with a maximum temperature of plus 31 degrees this afternoon as a result.
Environment Canada says overnight minimum temperatures of plus 16 degrees or less is expected, and relief from the heat will continue into Friday with cooler temperatures and the expectation of scattered showers.
Due to this, the weather agency says the duration of the heat event does not reach heat warning criteria, but these conditions can pose a health risk.
Environment Canada is asking that you drink plenty of cool liquids before you feel thirsty and also keep cool by dressing for the weather.