TORONTO, Ont. – Environment Canada has issued a special weather statement for the GTA warning of dense fog Thursday morning.

Environment Canada said visibility could be near zero in some areas, especially in Hamilton and London.

The special weather statement also covers other parts of southern Ontario, where fog patches began to develop Wednesday evening.

Porter Airlines advises its passengers to confirm their flights before heading out to the airport, as there could be delays.  
   
The special weather statement is in effect for:

• City of Toronto
• Halton – Peel
• York – Durham
• Barrie – Orillia – Midland
• Niagara
• Dufferin – Innisfil
• City of Hamilton
• Waterloo – Wellington
• London – Parkhill – Eastern Middlesex County
• Simcoe – Delhi – Norfolk
• Dunnville – Caledonia – Haldimand
• Oxford – Brant

However, the early-morning fog will give way to a warm fall day ahead. The forecast calls for plenty of sunshine and a high of 21 C.

It could be warmest day the city sees for a while. Temperatures are expected to cool off a bit on Friday, and then dip down to single digits over the weekend.