Air Canada is warning travellers there may be delays as eastern Ontario is coated in up to four millimetres of freezing rain.

The company issued a tweet Wednesday to notify customers "in case they wish to change their travel plans," according to an Air Canada spokesperson.

The alert spans four days, from Jan. 11 to 14, and covers Ottawa, Toronto and Montreal.

The fee normally associated with switching flights will be waived for travellers who do want to rebook —  for an economy fare, those fees are about $75 for a domestic ticket or $200 for an international ticket. 

Environment Canada has issued a freezing rain warning for eastern Ontario. Rain is expected to start Wednesday afternoon and continue into Thursday morning.