KITCHENER -- As a heat wave across much of Southern Ontario comes to an end, the wet weather is set to roll in.

Environment Canada has issued a special weather statement for Waterloo Region and Wellington County due to expected heavy rainfall.

The statement made on Thursday morning says there is potential for rainfall amounts of 20 to 40 millimetres to fall across some areas by this evening.

Although it notes there is still uncertainty about which area will receive the highest amount of rain.

Environment Canada says that rainfall warnings may be issued throughout the morning.

The expected cloud cover and heavy downpour is being attributed to the remnants of tropical depression Bertha, says the national weather authority.

Waterloo Region was under a heat warning for much of the week, with temperatures above 30 degrees Celsius on Monday and Tuesday.