If you are going to the CNE or other outdoor events in Toronto this weekend, bring an umbrella as wet conditions are expected, with up to 60 millimetres of rain expected.

Environment and Climate Change Canada (ECCC) has issued a special weather statement for Toronto and much of southern Ontario, advising of "significant rainfall" this weekend.

In the advisory, ECCC said the rain will begin Friday evening and continue into Sunday, with the heaviest rainfall expected on Saturday.

Toronto could see rainfall rates of up to 40 millimetres an hour and rainfall amounts of 30 to 60 millimetres this weekend.

"Locally higher amounts are possible Saturday afternoon and evening. This weather pattern typically brings rapidly changing conditions between sunny skies and heavy downpours," ECCC said in its advisory.

The federal agency added that rainfall warnings could be issued on short notice.

The Toronto and Region Conservation Authority said flooding is not currently expected in watersheds but GTA rivers may experience higher water levels and flows than normal.

"The combination of slippery and unstable banks, and changing water levels could create hazardous conditions near rivers or other water bodies," the TRCA said in a statement on Friday.

"All shorelines, rivers and streams within the GTA should be considered dangerous due to higher flows and changing water levels."

On Saturday, there is a risk of a thunderstorm in the morning and afternoon in Toronto, with a high of 27 C. Showers will continue on Sunday, with the temperature reaching a daytime high of 26 C.