Environment Canada says a special weather statement is in effect with torrential downpours expected Tuesday.

The weather agency says the rain is developing over southwestern Ontario and will reach the Golden Horseshoe Area after daybreak.

The rain is expected to be off and on with significant breaks from time to time.

They say the air mass will be very moist, torrential downpours giving significant rainfall amounts in relatively short periods of time. Some areas may get between 20 to 40 milimetres of rain by Tuesday evening but areas hit by severe thunderstorms may accumulate higher amounts.

The Hamilton Conservation Authority (HCA) is advising of the potential for significant increases in water levels and flows in the area watercourses. There is also potential for localized watercourse flooding of low-lying areas that typically flood during higher water levels.

The HCA is reminding residents to exercise caution near all water bodies and structures such as bridges, culverts and dams.