Toronto experienced a severe heat wave on Tuesday, with temperatures expected to reach 37 C and a humidex making it feel like 45 C. The city's second heat wave of July began on Monday and was forecast to end by Wednesday or Thursday night, with Tuesday being the hottest day.
The previous heat wave occurred from June 30 to July 4, with Environment Canada issuing an orange warning. This recent event prompted a lesser yellow warning. A meteorologist noted that while two heat events in July are not unusual, both have pushed the upper limits of typical Toronto heat.
The daily record high temperature for Toronto is 36.8 C, set in 1995. If Tuesday's forecast of 37 C is reached, the record will be broken. However, if temperatures only reach 36.5 C, it will still be exceptionally hot but not a record.
Several factors are contributing to the latest heat event, including a heat dome to the west. A strong area of high pressure in the mid and upper levels of the atmosphere has caused sinking air, which heats up and spreads east.
This heat wave is expected to be short-lived, with relief forecast for some regions in central and northeastern Ontario by Tuesday night. However, areas in southern Ontario will continue to experience hot temperatures into Wednesday or Thursday.
A third heat wave is predicted for Toronto in early August. While most of August is expected to be near normal, these high-impact heat events are likely to be relatively short-lived and not dominate the summer.
Other areas, such as Armstrong, Ont., have experienced historic heat, with temperatures reaching 40.8 C on Monday. This extreme heat is exceptional, especially given the lack of urban heat influences in the region.
