Environment Canada has a rainfall warning in effect for parts of southern Ontario including Sarnia-Lambton.
Periods of rain, at times heavy, are expected Thursday along with thunderstorms as a weather system tracks through the region from the American southwest.
Rainfall amounts will vary, averaging in the 20 to 30 mm range. However 40 to 50 mm (2 in) may be possible in some locales due to very heavy rainfall in embedded thunderstorms.
Localized flooding in low-lying areas is possible. The public is advised to stay clear of any washouts near rivers, creeks and culverts.