With another heat warning in effect this week, August 2022 will go down as one of the hottest on record. Calgary has spent more days in August under a heat warning than not, but few daily records were actually broken.
Officially, so far, it has been the fourth hottest summer on record when looking at the overall average temperature, which was 16.9 C.
"What's interesting about this year is there's no standout event that led to that. It's been this prolonged period of well above normal temperatures, much warmer than normal overnight lows," said Sara Hoffman, meteorologist with Environment and Climate Change Canada.
Environment Canada defines summer as the meteorological season (June 1 to Aug. 31) and calculates the average normal temperature by looking at the last 30 years of data to create an average, which works out to 15.3 C for Calgary.
"So we're 1.6 degrees above normal in Calgary with 137 years of data, so it doesn't seem like much but that places us ending the fourth warmest," Hoffman said.
The city has spent 27 days so far under a heat warning.
2022 heat warnings in Calgary
Number of heat warnings per year
Environment Canada issues a heat warning when daytime temperatures are expected hit 29 C or hotter and nighttime temperatures don't fall below 14 C for two days in a row. This is important because it allows residents to take extra precautions to cool off, especially at night when Calgarians are usually able to take advantage of the city's wide fluctuations between daytime and nighttime temperatures.
This year, the thermometer did not fall below 14 C on six days (so far). Looking at records, this puts 2022 in seventh place in overall, according to records from the Calgary International Airport that go back to 1881.
Even under the current heat warning, the temperature at YYC dipped to 7.7 C. However, the heat warning is based on an expected average across the city and there were areas where temperatures did not go below 14 C — particularly in more urban areas that experience a heat island effect, Hoffman said.
Calgary nights with a minimum temperature of 14 C or greater
This has led many Calgarians to seek relief from the heat, especially when trying to sleep at night.
"Ten or 20 years ago, air conditioning was not common in Calgary, and now it's become very commonplace for most homes," said Blake Shaffer, an assistant professor of economics at the University of Calgary.
Shaffer looks at electricity usage and has noted that Alberta is shifting from winter peak electricity usage to summer peak as more people are cooling their homes at night with air conditioning — and consuming more electricity — rather than just opening the windows.
"We still have a greater peak in the winter than we do in the summer, but it's getting very close," he said. "And that was not something you would have heard me say five years ago."
Shaffer recently posted Environment Canada data going back to 1881, noting that the number of nights above 10 C have increased even more.
"In many ways, it's even more stark than just looking at average temperatures. We're really seeing a significant shift in nighttime lows being higher than they have been in history," he said.
He chose this lower number because it's when his research determined that electricity demand switches from heating to cooling at 10 C in Alberta.
Environment Canada uses a slightly different data set that amalgamates the two weather stations at YYC, which would show a lower number of days above 10 C. This is because runways have expanded at the airport over the decades, influencing temperatures at the weather station. It is not consistent enough to be used for climate data.
Looking into the next week, the forecast shows warm days but cooler nights as more heat is reflected into the atmosphere at night.