Environment Canada has issued a special weather statement for the city of Thunder Bay, warning of the potential for significant rainfall Friday evening.
The national weather service issued the advisory, warning that an area of rain with embedded thunderstorms is expected to affect much of northwestern Ontario beginning this evening.
Rain may fall heavily and is expected to persist for much of the night before diminishing Saturday morning.
Environment Canada says a general 20 to 40 millimetres of rain is expected, but areas receiving several thunderstorms may see high amounts.
Find the most recent weather advisory at Environment Canada