Environment Canada is warning that areas of dense fog have developed in the Greater Toronto Area Tuesday morning.

Many portions of southwestern and southcentral Ontario, and north to Georgian Bay is enveloped in dense fog, the agency said.

Visibility could be reduced to 200 metres or less, according to the agency.

Porter Airlines is urging travellers to check their flight status as a result of the fog.

The airline has issued a special weather advisory for Toronto, Sudbury and and Windsor airports.

The fog is expected to lift later Tuesday morning.

Special weather statement for:

• City of Toronto
• Windsor – Essex – Chatham-Kent
• Sarnia – Lambton
• Elgin
• London – Middlesex
• Simcoe – Delhi – Norfolk
• Dunnville – Caledonia – Haldimand
• Oxford – Brant
• Niagara
• City of Hamilton
• Halton – Peel
• York – Durham
• Huron – Perth
• Waterloo – Wellington
• Dufferin – Innisfil
• Grey – Bruce
• Barrie – Orillia – Midland
• Peterborough – Kawartha Lakes
• Parry Sound – Muskoka