Impactful severe storm threat builds for parts of Ontario Friday

Stay alert for a potent line of strong to severe thunderstorms on Friday expected to sweep across southern Ontario

Southern Ontario is in for a day of active weather on Friday as instability builds across the region.

Severe thunderstorms are likely for some communities, carrying the risk for all hazards—including the potential for one or two tornadoes.

In addition to the storm risk, persistent rain could make for a slick drive for folks heading toward cottage country for the long holiday weekend.

Southern Ontario Friday thunderstorm energy - June 27, 2025

Be sure to keep up with the latest severe weather watches and warnings in your area. Know what to do if a tornado warning is issued for your location, whether you're at home, work, or on the road.

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Severe storms likely in southern Ontario on Friday

Showers will spread across the Greater Toronto Area during the morning hours as a warm front lifts across southern Ontario. Persistent showers are expected in northeastern Ontario in the morning, moving into the Ottawa region by the evening.

Ontario Friday severe thunderstorm risk - June 27, 2025

Unstable air moving in behind that warm front will set the stage for a round of strong to severe thunderstorms during the late afternoon and early evening hours on Friday.

A cold front pushing in from the west will collide with the unstable air and trigger a strong line of thunderstorms along the shores of Lake Huron and Georgian Bay.

Ontario Friday 7pm forecast storms and precipitation- June 27, 2025

These storms will develop amid an environment capable of supporting 2+ cm hailstones, strong wind gusts of 90-100 km/h, and the risk for embedded rotation. An isolated tornado cannot be ruled out. Damaging straight-line winds and microbursts are also a major threat that will be in play with these storms, which could cause major tree damage and outages.

We’ll see this line then move northeast and weaken as it approaches the Greater Toronto Area overnight.

Ontario forecast weekend rainfall totals - June 27, 2025

Saturday will feature improving conditions across most of southern Ontario. The persistent rain will ease across central and eastern portions of the province during the morning hours.

Scattered showers will remain possible through Saturday afternoon, but overall we’ll see conditions clearing up. Temperatures will finally inch into the lower 20s for folks in eastern Ontario.

Stay with The Weather Network for all the latest on conditions across Ontario.

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