Subway trains are bypassing at least two stations due to flooding.
The TTC says that trains are not stopping at Christie Station on Line 2 eastbound or at St. Patrick Station on Line 1 at all as a result of flooding.
It is not clear when full service will resume.
The issue comes after Toronto saw torrential rain at times on Monday afternoon.
Environment Canada had previously issued a rainfall warning shortly after 1 p.m., calling for rainfall amounts of between 40 and 60 millimetres.
The warning, however, was lifted at around 3 p.m.
A heat warning also remains in effect for Toronto.
The heat and humidity are acting as a “fuel for storms,” CP24’s Meteorologist Bill Coulter said Monday morning.
““Tuesday may offer rounds of strong storms as a cold front plows through. The air in the wake of the cold front will be much more manageable and offer relief from the oppressive heat and humidity,” Coulter said.