Kitchener, Waterloo and Cambridge have all declared snow events starting at 11:59 p.m. Thursday.
Forecasters say the region could get between 8 and 12 centimetres of snow.
Residents in all three cities are asked to move their parked cars from city streets by midnight.
The parking ban remains in effect for 24 hours.
Drivers who fail to follow the rules could receive an $80 ticket and have their vehicle towed at their expense.
The parking ban may be extended if weather conditions worsen.
