Environment Canada says a "major" late-winter storm is set to hit southwestern Ontario over the next few days.

The weather service has issued a special weather statement covering Windsor, Leamington, Essex County, Chatham-Kent and Rondeau Park for Wednesday and Thursday.

A low pressure system is developing near Texas and is expected to arrive Wednesday evening, and could bring up to 25 centimetres of snow — if the computer models are correct.

"Early indications are we could get over 15 cm in that overnight time frame Wednesday night into Thursday morning," Geoff Coulson, an Environment Canada meteorologist said.

"An additional five to 10 cm [is] possible during the day Thursday, again if the track holds to what it is right now," he said.

Since the storm is still forming, Coulson said there are still a few unknown factors, including the exact track of the storm. Depending on the direction of the storm it could mean some areas see more rain instead of snow.

"The exact track of the system will be key," Coulson said. "Even a variation at this point in the storm track of 50 to 100 kilometres could have a noteworthy impact on the amount and type of precipitation, because we will be right around the freezing mark when this thing hits."

A special weather statement is also in effect for parts of Sarnia, Petrolia and Lambton County.

Environment Canada says it will be issuing additional updates as the storm closes in.