A severe thunderstorm warning issued by Environment Canada for Toronto has ended.

Earlier in the day, the weather agency said isolated wind gusts of 90 km/h, frequent lightning, hail and torrential downpours may occur.

Heavy downpours are likely to cause flash floods and water pooling on roads, Environment Canada warned. 

Burlington Hydro reported that more than 13,000 customers were without power as of 4:30 p.m. Tuesday.

Due to the severe weather, power is out in a number of pockets in Burlington, including sections of mid to north parts of the City. No ETR at this time. Updates to follow.

— Burlington Hydro (@BurlingtonHydro) October 1, 2019

The severe thunderstorm warning ended around 6 p.m.

Earlier in the day, the GTA experienced summer-like temperatures.

But Anwar Knight, CTV News Toronto’s weather specialist, warned that things would change after calling it "one of the muggiest October days on record."

“We will go from a July-like day to a frost advisory tomorrow night for the north of the GTA,” Knight said on Tuesday. “It’s a one-day summer fling.”

The city saw a high of 31.2 C at Pearson Airport Tuesday afternoon, a new record for Oct. 1, but Environment Canada said the temperature is expected to drop to about 13 C in the evening.

The rest of the week is expected to be seasonally cool weather as the temperatures continue to plummet.