CBC meteorologist Peter Coade says the storm could be "crippling," and might bring as much as 40 or 50 centimetres of snow.
He said when he looks at his charts it reminds him of White Juan, the enormous blizzard that swept across Atlantic Canada in 2004 and dropped a metre of snow in some areas.
"It is rather too early to say with an exact degree of confidence at this time, but be aware that something could very well be affecting all transportation services on Wednesday in the Maritimes," Coade said.
Coade said his charts indicate that snow will begin after midnight in Nova Scotia and then spread to New Brunswick and Prince Edward Island Wednesday morning.
He said if the storm tracks inland the snow could turn to rain in Nova Scotia.