A low pressure system will push into the region on Tuesday, bringing as much as 15 millimetres of rain to some areas overnight.
The heaviest rain is expected to fall in the Greater Toronto Area, says Mark Robinson, a meteorologist at The Weather Network.
That's good news for residents still hoping to see some improvement in their lawns and gardens.
Southwestern and southeastern Ontario saw extremely heavy rain just before the long weekend, but the bulk of the rain missed Toronto. The city saw just over 32 millimetres of rain in the entire month of July -- a far cry from the monthly average of 74 millimetres.
Along with the rain comes the possibility of scattered thunderstorms -- and some could be severe.
Thunderstorms could begin popping up between Windsor and Hamilton Tuesday afternoon. The risk will continue overnight into Wednesday. According to a special weather statement issued by Environment Canada, the biggest threats will be damaging winds and large hail.
Unfortunately, the passage of the cold front will do little to dispel the humidity that has built back up since July's record-breaking heat wave.
On Monday, Environment Canada issued a humidex advisory for southwestern Ontario, including Windsor, Sarnia and the Niagara peninsula. Temperatures climbed into the 30s, with the humidex making it feel like 40.
The City of Toronto issued a heat alert, advising people to keep their air conditioners running, seek out opportunities to cool off and check on loved ones with known health issues.
It was the sixth time this summer Toronto has issued a heat alert in the interest of public health. The city has also issued five extreme heat alerts.
Temperatures will continue to hover in the high 20s, with humidex values in the low to mid-30s, through the weekend.