Toronto and Region Conservation Authourity has issued a flood warning for parts of the city.
The TRCA says the city has already received 25 – 50 mm of rainfall since early this morning and Environment Canada is forecasting another 15 mm of rainfall this afternoon.
Flooding of the Bayview Extension and the Metrolinx rail line within the lower parts of the Don River watershed have been reported.
That means there is a potential for flooding of low lying areas including the Don Valley Parkway.
The TRCA says water levels remain higher than normal resulting in dangerous conditions. That means flooding on roadways and underpasses could happen.
People are being advised to stay away from rivers and streams and exercise caution around all bodies of water.
The flooding has also caused a number of delays for GO Transit riders that use the Richmond Hill or Barrie lines.
Heavy rains have flooded an area along the Richmond Hill train corridor and the tracks cannot be used.
The Union Station 15:10, Richmond Hill GO 15:57, and Union Station 18:45 and Richmond Hill GO 19:33 have been cancelled.
The remaining four trains will operate by an alternate route along the Barrie line, serving Langstaff and Richmond Hill.
Passengers who usually travel to Oriole and Old Cummer may use their GO train tickets on the TTC.