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Live forecasts update automatically; written guidance last reviewed 16 June 2026 by the Canada Scene Weather Desk. Data from Environment and Climate Change Canada and other national met services via Open-Meteo.
Southern Ontario weather warnings are issued by Environment and Climate Change Canada when conditions threaten safety or travel, most often for winter storms, freezing rain, extreme cold, or summer thunderstorms. Check alerts before heading out, especially from November through March.
When do southern Ontario weather warnings typically occur?
The highest frequency of warnings runs from late November through early April, with freezing rain and snow squalls common along the Lake Erie and Lake Ontario shorelines. Summer months bring severe thunderstorm watches and heat warnings, particularly in July and August. For the most current conditions, visit our Ontario weather warnings today page.
What should travellers pack and plan for?
If you are driving through southern Ontario between December and March, keep an emergency kit with blankets, a shovel, and warm boots. March break travellers should expect lingering winter conditions, especially north of Highway 401. Snowbirds returning in April often encounter a mix of rain and cool temperatures. For a broader view, see our Canada weather warnings page.
Where can I find a southern Ontario weather warning today map?
Environment and Climate Change Canada provides the official map at weather.gc.ca. You can also check our Ontario weather warnings today page for a summary of active alerts across the region.
Are northern Ontario weather warnings different from southern?
Yes. Northern Ontario warnings focus more on extreme cold, blizzards, and ice roads, while southern warnings emphasize freezing rain, snow squalls, and lake-effect snow. Both regions use the same alert system from Environment Canada.
How long do southern Ontario weather warnings last?
Most winter warnings last 12 to 48 hours, though lake-effect snow events can persist for several days. Summer thunderstorm warnings are typically brief, lasting one to three hours. Check the weather warning page for real-time updates.