A mix of heavy rain and warm temperatures could bring flooding to the Greater Toronto Area overnight and into Friday.

Environment Canada has extended its earlier rainfall warning for Toronto, calling for strong winds and between 20 and 40 millimetres of rain. The storm system is gaining strength as it heads towards Lake Superior, according to the weather service, and is expected to be over northern Ontario and James Bay by Friday.  

Wet snow or rain is expected over almost all of southern Ontario overnight, turning to more rain as temperatures rise into Friday morning.  

'Significant' snow melt possible

Forecasters say the rain and possible thunderstorms will continue into Friday and may lead to “significant snow melt." 

A new layer of snow fell on Toronto earlier this week and, with temperatures expected to hover above freezing on Friday, there is fresh concern the city could experience some flooding.

Toronto Conservation Authority earlier issued a warning for high water levels, asking people to stay be cautious around streams and rivers.

The city worked to clear catch basins throughout the city on Thursday. Homeowners are advised to ensure that downspouts are clear and working properly and to clear snow and ice from outside foundation walls. Also, if your house is prone to basement flooding, move valuables to higher locations.

Electrical safety tips

Ontario's Electrical Safety Authority has reminded homeowners to be careful if floodwater gets close to wiring or equipment. The ESA recommends: 

  • If wiring or equipment gets wet, turn off the power for the entire house — by flipping the main switch on the electrical panel — until the equipment can be tested. 
  • If the water rises above outlets, covers power cords, or is near the service panel, contact your power company and have them turn it off at the source. 
  • Have a licensed electrical contractor test and perhaps replace flooded equipment and wiring before it used again. 
  • Remember that portable generators should not be connected to any flooded equipment.