THE CANADIAN PRESS — TORONTO - It was the hottest July 21 ever in many communities across southern and eastern Ontario and southern Quebec as the scorching heat and sweltering humidity sent thermometers soaring.

Environment Canada is still looking to see if any all-time records or July records were broken during the swelteringly hot day, but at least 17 cities and towns saw their previous single-day records broken.

The hottest temperature recorded Thursday anywhere in Ontario was a scorching 38.5 C in Grimsby, in the Niagara region.
Humidex values peaked in the mid- to upper 40s across Ontario and Quebec, with one climate station in downtown Toronto recording a humidex of nearly 51 C at 3 p.m.

Extreme heat and humidity warnings are slowly being called off as a weak front moves though, sweeping out the sultry air mass, Environment Canada said in a statement.

In Sherbrooke, Que., Thursday was the hottest July 21 the city had seen since 1919, when it was 32.2 C. The temperature reached 32.9 C in the city on Thursday.

The weather service had predicted temperatures as hot as 39 C in Windsor, Ont., but the hottest southern border city got was 37.6 C, which still broke its previous single-day record of 35.4, reached on July 21, 1998.

There were other single-day July 21 records broken Thursday, many of them from a hot spell in 1955:

• Sarnia, Ont., reached 36.1 C, breaking the old record of 34.5 C from 2002
• Harrow, Ont., reached 37.8 C, breaking the old record of 37.2 C from 1930
• Point Pelee, Ont., reached 32.8 C, breaking the old record of 32.4 C from 2002
• London, Ont., reached 36.7 C, breaking the old record of 34.4 C from 1955
• Delhi, Ont., reached 36.3 C, breaking the old record of 34.4 C from 1955
• Woodstock, Ont., reached 35 C, breaking the old record of 33.3 C from 1955
• Kitchener, Ont., reached 35.7 C, breaking the old record of 35.6 C from 1955
• Hamilton's Mount Hope station reached 36.4 C, breaking the old record of 32.7 C from 2002
• Vineland, Ont., reached 37.4 C, breaking the old record of 36.1 C from 1955
• Grimsby, Ont., reached 38.5 C, breaking the old record of 36.1 C from 1955
• Toronto's Pearson airport station reached 37.9 C, breaking the old record of 35.6 C from 1955
• Toronto's Buttonville airport station reached 37 C, breaking the old record of 33.8 C from 2005
• Toronto's downtown station reached 38.2 C, breaking the old record of 34.4 C from 1955
• Toronto's island airport station reached 36.5 C, breaking the old record of 32.4 C from 1987
• Oshawa, Ont., reached 37.1 C, breaking the old record of 35.6 C from 1955
• Kingston, Ont., reached 32.6 C, breaking the old record of 31.7 C from 1972
• Petawawa, Ont., reached 35.7 C, breaking the old record of 35.6 C from 1955
• Montreal reached 35.6 C, breaking the old record of 35 C from 1955