Ottawa could receive up to 40 mm of rain Tuesday and Wednesday

Fog enshrouds the Peace Tower on Parliament Hill, Tuesday, Dec. 10, 2024 in Ottawa. (Adrian Wyld/THE CANADIAN PRESS)

Ottawa is set to receive a soaking from Mother Nature, with up to 40 mm of rain possible over the next two days.

Environment Canada has issued a rainfall warning for Ottawa and eastern Ontario, calling for rain, heavy at times, tonight and on Wednesday.

"Rain, at times heavy, will start this evening. Rain may taper off on Wednesday morning, but it is expected to intensify again on Wednesday afternoon," the weather agency said in a statement.

"Total rainfall amounts of 30 to 40 mm are possible by Wednesday evening before rain changes to snow as temperatures drop below the freezing mark. Given the frozen ground, significant amounts of water due to snowmelt and rain could accumulate on roads and low-lying areas."

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The rainfall warning is in effect for Brockville-Prescott, Gananoque, Maxville-Alexandria, Merrickville, Kemptville, Morrisburg-Long Sault, Smiths Falls, Perth and Prescott and Russell.

The City of Ottawa is asking people to ensure catch basins are clear near their homes and able to take in water.

"With over 100,000 catch basins in the city, we cannot do it alone and would appreciate any support you can offer," the city said on its website.

City crews are focusing on cleaning up and treating residential streets and sidewalks to ensure any ice build up is addressed "as well as tidy up some areas" from Tuesday's storm, according to the city's website.

Environment Canada has also issued a fog advisory for Ottawa. 

"Near zero visibility in fog is expected or occurring. Visibility may temporarily improve during the afternoon before conditions worsen again this evening," Environment Canada said. "The fog is expected to lift Wednesday afternoon."

A total of 4.2 cm of snow and 1 mm of rain was recorded at the Ottawa Airport on Monday, with light freezing drizzle continuing overnight and Tuesday morning.

Ontario Provincial Police reported nearly 100 collisions between 1 p.m. Monday and 9 a.m. Tuesday. Police say there were no injuries but are advising drivers to adjust to winter conditions.

The forecast calls for mainly cloudy today with a 40 per cent chance of drizzle or rain. High 5 C.

Rain tonight. Environment Canada is calling for 10 to 15 mm of rain. Low 2 C.

Rain continuing on Wednesday, with another 5 to 10 mm expected. High 4 C.

Thursday will see a mix of sun and cloud with a chance of flurries. High -3 C.

The outlook for Friday calls for a mix of sun and cloud. High -4 C.

Saturday will be mainly cloudy with a 40 per cent chance of flurries. High -6 C.

The normal temperatures for this time of year are a high of -3 C and a low of -10 C.

Rising water levels

The Rideau Valley Conservation Authority is warning the heavy rain and the mild temperatures will cause water levels to rise.

"With the expected rain and snowmelt, significant flooding is not anticipated, however, water levels across all waterways in the Rideau Valley Watershed are expected to rise in the coming days," the conservation authority said.

People are urged to exercise "extreme caution around all waterbodies."