Overview

• The heat dome remained stationary over Ontario and Quebec on June 23, driving daytime highs above 30 °C with humidex values up to 45 °C. Environment Canada issued severe thunderstorm and tornado warnings for northern Ontario as heat and humidity fuel atmospheric instability.
• A late Saturday storm in Mattawa led to the closure of Highway 17, evacuation of nearly 300 people from two provincial parks and a state of emergency in the Municipality of Calvin.
• Heavy rainfall advisories in southern Alberta have lifted, but the Calgary Fire Department continues to warn residents to avoid the fast-flowing Bow River.
• Lake Diefenbaker is forecast to rise by more than a metre this week while other regions experience below-normal temperatures and precipitation shifts ahead of the June 25 air mass change.