A rainfall warning is in effect for Ottawa, Gatineau, and parts of eastern Ontario and southern Quebec.
Environment Canada says eastern Ontario can expect between 50 and 80 mm of rain between Thursday night and Saturday night. Some regions may see upwards of 100 mm, especially communities along the St. Lawrence River. The rainfall is due to a moisture laden low pressure system moving southeast of Lakes Erie and Ontario into Northern New York State by Friday and Southeastern Quebec Saturday.
19.2 mm of rain fell on Ottawa on Thursday.
Environment Canada meteorologist Ria Alsen tells CFRA the risk of flooding is reduced because rain will be falling more slowly over a longer period of time. However, some low-lying areas may experience localized flooding, and streets with clogged sewer grates may also have trouble.
"The leaves are falling now, and they clog up gutters and sewer grates. It's a good idea to make sure the sewer grates in your neighbourhood are clear of the leaves, so the rain has place to go."
The record rainfall in Ottawa for October 21 is 58.8 mm, recorded in 1995.
Rainfall warnings are in effect in the following areas in eastern Ontario:
Gatineau is also affected, and rainfall warnings stretch northeast along both sides of the St. Lawrence to beyond Montreal.
Visibility on the roads may be reduced slightly in some areas.