4:25 AM EDT Wednesday 27 June 2018
Special weather statement in effect for:
Niagara Falls – Welland – Southern Niagara Region
St. Catharines – Grimsby – Northern Niagara Region
Potential for heavy thunderstorms today followed by an extreme heat event for the Canada Day long weekend.
Showers and thunderstorms are forecast to affect Southwestern Ontario today. The heaviest storms are expected this morning through midday. Total local rainfall amounts could be in the 30 to 50 mm range, with higher amounts possible under the heaviest storms.
A persistent southwest flow is then forecast to develop, bringing hot and humid air from the Gulf of Mexico. Beginning Friday or Saturday and continuing through the Canada Day long weekend, expected daytime highs are in the low to mid thirties with humidex values into the mid forties. Overnight low temperatures will only fall to the low twenties, providing little or no relief from the heat.
There is still uncertainty regarding when the heat event will come to an end. Current indications suggest the heat could persist into the middle of next week.
This will likely be the most significant heat event of the season thus far. Heat warnings will be issued as the event draws nearer.
Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to ONstorm@canada.ca or tweet reports using #ONStorm.