Fog, 10-15 mm of rain in the forecast for Ottawa today

The Rideau Canal in downtown Ottawa. (Andrew Adlington/CTV News Ottawa)

It will be a foggy and rainy day in Ottawa, before snow returns to the national capital region tonight and on Thursday.

Environment Canada has issued a rainfall warning and a fog advisory for Ottawa and most of eastern Ontario.

Ottawa is expected to see another 10 to 15 mm of rain today, before precipitation changes to snow this evening.

"Rain is forecast to redevelop near noon today," Environment Canada said in a statement.

"The rain will likely continue through the afternoon before transitioning to wet snow this evening. Given the frozen ground, water due to rain and snowmelt could accumulate on roads and in low-lying areas."

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Ottawa received 9.2 mm of rain on Tuesday.

The forecast calls for mainly cloudy with a 60 per cent chance of rain or drizzle this morning. Rain beginning near noon. High 3 C.

Rain changing to snow mixed with rain this evening. It will end near midnight then cloudy overnight. Ottawa is expected to receive 5 mm of rain and 2 cm of snow. Low -3 C.

Flurries are in the forecast for Thursday. Amount 2 C. High -3 C.

Friday will be sunny. High -4 C.

The outlook for Saturday calls for sunshine. High -6 C.

Sunday will be cloudy. High -1 C.

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

Fog Advisory

Environment Canada has issued a fog advisory for Ottawa, warning it will be "near zero visibility" today.

"Locally dense fog is forecast to persist into this morning before dissipating," the weather agency said. "Visibility may be significantly and suddenly reduced to near zero. Travel is expected to be hazardous due to reduced visibility."

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."