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Cornwall to Montréal

Warnings

Forecast

Marine Forecast

Issued 03:00 AM EDT 21 July 2026

Today Tonight and Wednesday.

Strong wind warning in effect.

Wind light increasing to southerly 15 knots early this morning and to south 15 to 25 early this afternoon. Wind becoming south 15 near midnight. Wind southwest 10 to 20 Wednesday.

Showers this afternoon tonight and Wednesday. Risk of thunderstorms late this afternoon and this evening. Visibility as low as 1 mile in showers.

Extended Forecast

Issued 06:00 AM EDT 21 July 2026
Thursday Wind southwest 15 to 20 knots diminishing to southwest 10 to 15 late in the day.
Friday Wind southwest 10 to 15 knots.
Saturday Wind light.

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

There is no ice forecast issued for this area.

Warnings

Warnings (In effect)

Strong wind warning in effect

Cornwall to Montréal

Issued 03:00 AM EDT 21 July 2026

'Strong' winds of 20 to 33 knots are occurring or expected to occur in this marine area. Please refer to the latest marine forecasts for further details and continue to monitor the situation through Canadian Coast Guard radio.

Watches (In effect)

Squall watch in effect

Cornwall to Montréal

Issued 10:03 AM EDT 21 July 2026 Today, between 3 pm and 8 pm, conditions will be favourable for the development of squalls accompanied by gusts of up to 45 knots and frequent lightning.

Vessels without lightning protection should make their way to shore immediately. Mariners are advised to prepare for potential squalls. Vulnerable vessels are most at risk and should seek safe harbour if underway. Consider delaying or postponing travel in areas under the Squall Watch.

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 AM EDT 21 July 2026 Today Tonight and Wednesday At 3:00 a.m. EDT today departing low 993 mb located off Labrador.

At 3:00 a.m. EDT today ridge located on a line north-south over
Sept-Îles.
By 8:00 p.m. EDT tonight dissipating ridge located from Newfoundland
to Natashquan.

At 3:00 a.m. EDT today trough located on a line north-south over
Lake Superior.
By 8:00 p.m. EDT Wednesday trough located on a line north-south
over Tadoussac.

Great Lakes - Lake Huron Area

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Marine Weather for Canada

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