Environment Canada has issued a weather advisory covering London and most of southern Ontario saying an incoming weather system from the central United States is expected to bring significant rainfall to the region starting Wednesday night.
According to the national weather agency, about 15 to 25 mm of rain is expected to fall across the region Wednesday night into early Thursday as the system makes its way east across southern Ontario.
The advisory says fog patches are also expected in the overnight hours, which may cause visibility issues in some areas.
On Thursday, forecasters say London will see periods of rain turn to periods of snow in the afternoon hours, with temperatures falling to zero. A risk of freezing rain is also expected later in the afternoon and early evening.