11:35 PM EDT Thursday 11 July 2024 Heat Warning in effect for: Summer Beaver - Wunnummin Lake - Kingfisher Lake A heat event is expected to persist into the weekend. A hot airmass has arrived over northwestern Ontario. Daytime maximum temperatures are expected to be near 30 degrees Celsius with humidex values near 35. There will be little relief during the overnight as minimum temperatures are expected to be near 19 degrees Celsius. A cooler airmass is expected to arrive Sunday night or Monday. Extreme heat can affect everyone?s health. Drink plenty of water regularly, even before you feel thirsty to decrease your risk of dehydration. Thirst is not a good indicator of dehydration. Reduce your heat risk. Schedule outdoor activities during the coolest parts of the day. Never leave people, particularly children, or pets inside a parked vehicle. Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to ONstorm@ec.gc.ca or tweet reports using #ONStorm .