A heat wave is expected to come to an end after thunderstorms swept through southern Ontario on Thursday evening.

The first full day of summer saw the temperature hit 33.8 C in Toronto by the mid-afternoon, slightly lower than the record-setting heat the city saw the day before.

On Thursday, it was even hotter in Markham, where the temperature stood at 34.6 C.

However, the heat began to diminish as thunderstorms rolled through the GTA on Thursday evening, with the temperature falling to the lows 20s. 

A swath of southern Ontario from Windsor to Ottawa was under a series of severe thunderstorm watches and warnings, but they have all been lifted. 

A severe thunderstorm watch in Toronto was lifted by mid-evening.

The projected daily high for Friday is a mere 25 C, nine degrees lower than where the temperature was on Thursday afternoon.

More hot weather to come

The country's top weather guru says the hot weather is far from over.

"There's no guarantee with weather â€” not in Canada, maybe in Malta or Cyprus or Honolulu…But our models are showing that we think that July and August and early September look like it's going to be warmer than normal from coast to coast to coast," said Dave Phillips, senior climatologist at Environment Canada.

The past three days have been "almost a dry run, or the opening act" to weather ahead, said Phillips.

Toronto set a daily record Wednesday during the second day of the heat wave.

Environment Canada says it recorded a high of 34.6 C at Pearson International Airport at the height of the heat wave. That's slightly higher than the old record of 34.4 C recorded in 1949 and in 1988.

With files from The Canadian Press