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

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