Whew! That was our hottest July since 1921
Study suggests we can expect lots more sweltering weather in the years ahead
July 2020 isn’t the hottest July on record in Ottawa, but you’d have to have been alive in 1921 to have experienced a more sweltering one in the capital.
“We look at records in Ottawa that go back almost 150 years, almost since Confederation,” Environment and Climate Change Canada senior climatologist David
Phillips said. “There’s only been one other month that comes close to 1921, that July, and it’s this July.”
Measured at the Central Experimental Farm — and factoring in a forecast high of 27 C Friday — the average afternoon high for July 2020 was 30.1 C, the average overnight low was 18.3 C and the overall average was 24.2 C.
In July 1921 at the farm, the average high was 31.4 C, the average low was 18.5 C and the overall average temperature was 24.9 C during a summer in which extreme heat settled over the eastern half of Canada and northeastern United States.
Meanwhile this summer, in the eight weeks since June 6, precipitation has been about half of normal as high temperatures made the demand for water spike.
As July ended, Ottawa was finally seeing so-called normals for this time of year — highs of 26 C and lows of 16 C.
“Now it has cooled off a little bit, it is much more comfortable,” Phillips
said, but “I looked at the latest forecast for Ottawa and it shows the month of August being warmer than normal and drier than usual.”
August tends to be about a degree cooler than July “but it still can have a significant number of days above 30 C.”
Saturday is expected to hit 30 C, but the forecast includes temperatures in the low to mid-20s and the risk of rain from Sunday through Thursday.
Using measurements from the Ottawa International Airport, where records go back to 1938, this summer has seen a string of record-breaking daily highs, lingering heat waves and warm nights that make it hard to cool off.
To blame? A dome of high pressure that Phillips likens to the Rogers Centre sitting over Canada’s eastern half, keeping weather systems from moving.
Contributing factors may include sea surface temperatures and a jet stream that is normally farther north of us, but the summer of 2020 could be a “dress rehearsal” of what climate change models suggest we can expect in the future.
A study funded by the National Capital Commission and the City of Ottawa this year, for example, predicted 2.5 times more days with highs of 30 C or higher by the 2030s and 6.5 times as many by the 2080s.