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Cornwall to Montréal

Forecast

Marine Forecast

Issued 03:00 PM EDT 21 June 2025

Tonight and Sunday.

Wind light increasing to southeast 10 to 15 knots early this evening and to westerly 15 to 20 near midnight. Wind diminishing to west 10 to 15 Sunday afternoon and to light Sunday evening.

Showers overnight and Sunday morning with a risk of thunderstorms. Scattered showers Sunday evening. Visibility as low as 1 mile in showers.

Extended Forecast

Issued 06:00 PM EDT 21 June 2025
Monday Wind light increasing to southwest 15 to 25 knots in the afternoon.
Tuesday Wind southwest 10 to 20 knots.
Wednesday Wind northwest 15 knots veering to northeast 10 to 15 late in the day.

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Weather Conditions

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Map of Great Lakes - Lake Huron marine weather areas Cove Island Goderich Oshawa Executive Airport CFB Trenton Western Islands Wiarton Airport Point Petre Lake Simcoe Regional Airport Parry Sound Harbour Toronto City Centre Airport Muskoka Airport Lagoon City Brockville Hamilton Munro Int'l Airport Sarnia Chris Hadfield Airport Tobermory Cobourg Harrow AAFC Long Point Port Weller Burlington Lift Bridge St. Catharines / Niagara District Airport Southeast Shoal Point Pelee Vineland Station Welland-Pelham Erieau Windsor Airport Port Colborne Killarney South Georgian Bay - 45143 Grimsby - 45139 Georgian Bay - 45137 Prince Edward Point - 45135 Port Stanley - 45132 Lake St Clair - 45147 South Lake Huron - 45149 Sault Ste. Marie Airport Lake Simcoe - 45151 Collingwood Greater Sudbury Airport North Bay Airport Kingston Airport Peterborough Municipal Airport Grenadier Island Port Colborne - 45142 Great Duck Island Ajax - 45159 Gore Bay-Manitoulin Airport North Channel - 45154 Lake Nipissing - 45152
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Ice Conditions

There is no ice forecast issued for this area.

Warnings

Watches (In effect)

Squall watch in effect

Cornwall to Montréal

Issued 4:40 PM EDT 21 June 2025 Overnight tonight, conditions are favourable for the development of squalls with wind gusts up to 50 knots, frequent lightning and hail.

Mariners are advised to prepare for potential squalls. Vulnerable vessels are most at risk and should seek safe harbour if underway.

Please continue to monitor alerts and forecasts issued by Environment Canada. For more information monitor Canadian Coast Guard radio or Weatheradio stations.

Synopsis

Technical Marine Synopsis

Issued 3:00 PM EDT 21 June 2025 Tonight and Sunday At 3:00 p.m. EDT today departing low 995 mb located off Labrador.

At 3:00 p.m. EDT today ridge located from Hudson Bay to Maine.
By 8:00 p.m. EDT Sunday weakening ridge located on a line
north-south over Newfoundland.

At 8:00 p.m. EDT tonight low located south of James Bay.
By 8:00 p.m. EDT Sunday weakening low located over New Brunswick.

Great Lakes - Lake Huron Area

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