A huge 30 C temperature swing will take Hamilton out of this week's deep freeze straight into a rapid thaw made worse by rain.

This drastic weather change leaves city staff moving from extreme weather cleanup to bracing for a flooding. Hamilton’s conservation authority is also advising residents to exercise caution around all water bodies due to expected rising water levels from rain and an expected thaw.

'Crews are working proactively to clear catch basins and inspect flooding hot spots across the city.'- Kelly Anderson, Hamilton public works

“While some Hamilton roads crews are continuing cleanup efforts across the city, some have now switched gears to focus on preparing for the milder temperatures this weekend,” says Kelly Anderson, the city’s public works department spokesperson. “Crews are working proactively to clear catch basins and inspect flooding hot spots across the city.”

Hamilton broke a weather record Tuesday with temperatures dipping to -24 C (wind chill -41 C) making it the coldest January 7 on record. Residents had to deal with frigid icy conditions, frozen sidewalks and burst pipes.

The cold weather alert affecting Hamilton and most of Southern Ontario increased the risk of frostbite and  hypothermia, while city paramedics reported higher slip-and-fall incidents.

Flood risk

Now, predicted warmer weather and a weekend downpour are creating a flood risk in the city. Temperatures are forecast to reach a high of 7 C on Saturday, and 10 to 30 mm of rain is predicted to fall on Friday and Saturday, with most of the rain occurring on Saturday. 

The melting of the city snowpack increases the risk of flooding. Environment Canada also warns there is a risk of freezing rain starting Friday night.

The changes may be drastic but not quite unexpected for the season, says Ross Hull, CBC News meteorologist.

“The winter is often a time of extremes when it comes to weather. It’s not necessarily unusual to experience wide contrasts in weather in the Southern Ontario region,” Hull said.

This week, however, what many cities experienced was an extreme weather event. “It wasn’t just how cold it was, it was the wind. Also, it was how quickly the arctic air moved in. Within a matter of hours, we were below freezing.”

Residents are advised to prepare for the weekend weather. It is a good idea to clear snow, ice and debris from the catch basins to prevent water buildup or ice jams.