It will be a wet and windy Halloween across the GTA, with snow even possible in some areas north of Toronto.
Environment Canada issued a special weather statement on Wednesday morning, warning of "potentially significant rainfall" for southern Ontario.
The weather agency said a low pressure system, approaching from the southwest, is forecast to bring rainfall totals between 30 mm and 50 mm.
Environment Canada said the heaviest rain is forecast for Thursday afternoon. The rain is expected to taper off by Friday morning.
"There will be no treats from Mother Nature this Halloween," CTV News Toronto weather specialist Anwar Knight said.
"It's going to be wet with periods of rain and breezy with a temperature hovering around seven degrees."
"The worst of the weather will come after trick-or-treating, on Thursday night into Friday morning, with wind gusts 70 to 80km/h an hour."
"This could mean some power outages with tree limbs being knocked down. For those who haunt their houses with decorations, plan to take them down Thursday night because of the strong winds."
"As cold air rushes in on the back side of this storm, wet flurries are also very likely - especially in the higher elevations north of city."
Motorists are being warned to turn headlights on and maintain a safe following distance if visibility is reduced, especially during peak trick-or-treating hours.
"For those who are going out, special care should be exercised. A flashlight, or some reflective tape should be included so trick-or-treaters can be seen," Knight said.
"Kids may be wearing extra gear to keep dry, and will be excited and won’t be looking out for cars, so it’s important they remain visible."
