Environment Canada has a rainfall warning in effect from Regina west to the Manitoba border. Another 15 millimetres are expected to fall across the areas hit hardest on the weekend.
Heavy downpours could cause flash floods and submerged roads, the weather agency has warned. The rain should taper off later Monday afternoon.
In southwestern Manitoba, however, the sun won't likely be seen until late Tuesday or Wednesday. Environment Canada expects 10 to 15 millimetres of rain on Monday and a 60 per cent chance of more rain Tuesday.
Due to the overland flooding and road closures, mail service has been cancelled for many rural communities in southwestern Manitoba and southeastern Saskatchewan.
Canada Post issued an alert Monday morning, noting that "mail delivery will resume as soon as it is safe to do so."
States of emergency
States of local emergency are in effect in 24 municipalities in Manitoba, and many parts of southeastern Saskatchewan.
Some areas got more than 200 millimetres of rain over the weekend, and overland flooding has forced the closure of several roads in both provinces.
In Saskatchewan — Regina and Yorkton — the sanitary and storm sewer systems are taxed to the limit, prompting Regina's fire department to urge people not to shower or even flush their toilets.
In Brandon, Man., the airport shut down all flights in and out of the city after the main access road became impassable due to the water.
But on Monday, airport staff set up a circuitous detour to get passengers to the building and WestJet announced it was resuming some flights.
Detour signs are being put up along the Trans-Canada Highway and Highway 10, and airport staff will be out to direct traffic.
Volunteers and municipal crews have been out sandbagging in many communities around Manitoba — mostly in the southwest corner but also in the Whiteshell cottage country — trying to protect homes from rising rivers and creeks.
The rainfall amounts weren't as heavy in Winnipeg — 50 mm compared to 144 mm in Deloraine — but the city was battered by wind, instead.
The gusts hit 81 km/h at times and a city spokesperson said Monday that some 400 calls came in about toppled trees or branches.