Flood watches issued last week by the Lakehead Region Conservation Authority remain in effect Monday for Thunder Bay and other area communities.
The conservation authority said that through 2 p.m. Sunday, 10 mm of rain fell in a 24-hour period. The rain continued overnight Sunday and into Monday morning.
The conservation authority expects 70 mm of rain to fall in the next 48 hours.
Just as residents headed into the much-anticipated long weekend, officials warned heavy rainfall could cause flooding in some areas.
Officials are warning the public to be careful around waterways, and to keep an eye on weather forecasts over the long weekend.
"Use caution around waterways. They could rapidly increase in height and speed and velocity," said Bill Bartley, chair of the authority.
The flood watch covers Thunder Bay, Neebing, Oliver Paipoonge, Shuniah, and the townships of O'Connor, Conmee, Gillies and Dorion. It will remain in effect until Tuesday.