It's not been record-setting, but metro Detroit's summer has been a hot one

Heat waves have been getting longer, more frequent and more intense across the globe — and metro Detroit is no different. This summer in Southeast Michigan has been one of extended periods of extreme heat, punctuated by a few cooler days, and averages temps well above normal.

Detroit’s average temperature over the last three months was 69 degrees, the fifth highest average through that period over 150 years of record keeping. Average temperatures have been in the 97th percentile of heat, meaning that compared to past averages, this year's temperatures are among the top 3% ever recorded.

Average temperatures hovered above their historic normal on around two-thirds of days between May and late July, according to data from the National Oceanic and Atmospheric Administration. The daily average is calculated by adding the daily maximum and minimum temperatures and dividing by two.

Normal temperatures, calculated every 10 years based on the prior 30 years of historic weather and climate data, are created by the National Center for Environmental Information and used to provide a ruler for comparison. Normals were most recently updated in 2020.

Detroit hasn't had any record-breaking hot days since the start of summer. Instead, it's been a summer of consistent heat: sustained stretches of hotter than normal days. In June, there were four days where temps hit over 90 degrees — normal temperatures don't reach 90 at all in June, and the highest normal daily temperature for the month is 85 degrees. In May, there were seven days where temperatures reached more than 80 degrees, compared to a normal maximum of 75 in the month.

It’s hard to pinpoint exactly what's causing the elevated temperatures in Detroit, said Sara Shultz, a meteorologist with the National Weather Service.

“It’s all about the weather systems and the jet stream, and the ocean temperatures,” she said. “All that comes into play.”

Across the nation, the Southwest and East have seen even more dramatic heat trends this summer — cities in Florida and up through the mid-Atlantic are in the 99th percentile with their average temperatures. Phoenix, Las Vegas and Sacramento are also experiencing 99th percentile averages.

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The weather Detroit is experiencing is closer to normal for a city 263 miles away: this would be an average summer in southern Ohio, rather than southeast Michigan.

June’s monthly average was two degrees above normal and May’s was even more significant: a full four degrees above normal. July’s average temperature has been a single degree below normal so far, but a hot flash expected this weekend and through the end of the month could push that over the top.

“We do have warmer temperatures coming (later this month),” said Shultz. “It’ll be interesting how that plays a role in our monthly average.”

This article originally appeared on Detroit Free Press: It's not been record-setting, but metro Detroit's summer has been a hot one