Your weather when it really mattersTM


Please choose your default site


Asia - Pacific


Damaging winds, hail possible in Ontario with severe thunderstorm risk

Wednesday, June 10th 2020, 7:07 am - What is left of Cristobal will bring rain, building heat, humidity and the risk of severe thunderstorms to southern Ontario by mid-week

EDITOR'S NOTE: This story is no longer being updated. Read the most updated version here

Severe thunderstorms are possible across southern and central Ontario on Wednesday and the main hazards include powerful wind gusts, heavy rain and large hail. Certain areas are seeing a greater chance of severe weather than others and meteorologists warn that there is the potential for a tornado or two in the high-risk areas. Heat warnings continue to be widespread across the region and the humidity will continue to climb on Wednesday. Details and timing, below.

Visit our Complete Guide to Summer 2020 for an in-depth look at the Summer Forecast, tips to plan for it and much more


  • Remnants of the former Tropical Storm Cristobal will bring moisture, summer heat and instability to southern Ontario
  • Humidity making it feel hotter than 30 for many regions
  • Temperatures begin to cool on Wednesday
  • Keep on top of weather ALERTS in your area


The first round of rain and thunderstorms in Ontario will begin pre-dawn Wednesday morning as a warm front tracks across the southwest. The warm front will move through the GTA during the early morning hours and then into eastern Ontario.

This means that it will be more humid than it was on Tuesday, which primes the atmosphere for severe thunderstorms in some regions.


The greatest threat for severe thunderstorms will be in southwestern Ontario and upwards into central Ontario. The main threats associated with the storms in these regions include strong wind gusts, heavy rain, large hail, and even the risk of a tornado or two. For the rest of southern Ontario, the threat is still there but is slightly lower.

Storms will be scattered in the afternoon but once the cold front moves through, a squall line will develop and make the storms more widespread. A squall line is a narrow band of convective storms that can produce damaging winds, heavy rain, frequent lightning and occasionally hail and tornadoes.

As for temperatures, Wednesday will be even hotter than Tuesday, with daytime highs at or above the 30-degree mark feeling more like 40 for the southwest and parts of the GTA, with eastern Ontario also feeling like the mid-30s.

Environment and Climate Change Canada (ECCC) has issued heat warnings covering the GTA and southwest, warning people to be mindful of the danger.


"The risks are greater for young children, pregnant women, older adults, people with chronic illnesses and people working or exercising outdoors," the agency says. "Never leave people or pets inside a parked vehicle. Outdoor workers should take regularly scheduled breaks in a cool place."


Behind the system, much cooler weather looms for the end of the week and unusually chilly weather is expected for the weekend with temperatures 5-10 degrees cooler than seasonal. The below seasonal temperatures will continue into early next week, but with abundant sunshine, followed by a warming trend for the middle of the week.

Stay tuned to the Weather Network for the latest forecast updates.

Default saved

Search Location


Sign In

Please sign in to use this feature.