Large parts of Canada are experiencing a severe heatwave accompanied by thunderstorms and deteriorating air quality, amid expectations of record temperatures. Authorities urged Toronto residents to stay home after the city topped the global list for worst air quality due to wildfire smoke, and issued an orange alert urging residents to avoid sun exposure and drink plenty of water. Warnings cover several provinces with forecasted heat index of around 45 degrees Celsius, along with the possibility of tornadoes in parts of Quebec and New Brunswick. Experts indicate that the extension of a high-pressure system from the United States into Canada contributed to temperatures rising above normal levels.