Breaking down Salt Lake City’s record-breaking temperatures: What does the data say?

There’s no doubt about it: It’s been incredibly hot in Salt Lake City this summer.

On Wednesday, the city reached 107 degrees, torching the record for the hottest September day ever, set just the day before. Wednesday also marked the 34th day of triple-digit heat here — the ninth in a row, a streak that pushed 2022 well past the record of 21 triple-digit days set in 1960 and matched again in 1994 and 2021.

“Highs are starting to get precariously close to annual all time records, something that should be practically unheard of at the beginning of meteorological fall,” Monica Traphagen, lead meteorologist at the Salt Lake City National Weather Service, wrote in a forecast.

It’s concerning, she said. The record-heat has also inspired a lot of questions, including: Is it really a 100-degree day in Salt Lake City if that temperature was recorded at the airport, but not downtown, or further east?

Does placement of the airport temperature gauge skew the data? Why are these readings done at airports anyway? Here are some answers.

Are temperatures higher at the airport?

The whole west side of the valley is typically a little bit warmer than the rest of the county, Traphagen said. It’s partly because of its lower elevation and partly because it generally has less irrigation and trees.

Studies have found that areas with more concrete and asphalt are hotter than areas with more abundant green space and tree canopy. The city is currently working to plant more trees on the west side.

Utah’s warming climate also plays a role, according to the National Weather Service.

The West is getting hotter and drier. Utah is no different. In Salt Lake City, in particular, the Great Salt Lake is lower than it’s ever been, causing the typical lake-breeze fronts to bring hotter air into the valley, according to the weather service.

Why take the temperature at the airport?

The weather service has been taking temperature measurements at the airport since 1928, and officials say it remains there so observation can stay consistent over time. Researchers set up the current temperature gauge in 1995, though it’s been moved once since then, Traphagen said.

There’s also some symbiosis between the weather service and the airport.

If you’ve ever taken off from a high-altitude airport in the heat of summer, you may have noticed an elongated taxi before takeoff, or a slower ascent. That’s due to a phenomenon called “hot and high,” which makes it harder for planes to gain speed and lift if they’re taking off in hot or high conditions.

Airport weather sites help collect the accurate weather information that pilots need, Traphagen said.

In 2010, crews moved the Salt Lake City airport’s current temperature gauge about three-quarters of a mile south from its original spot near the center of the runway. Traphagen said that relocation didn’t have that much of an impact on temperature readings, since the device has always been maintained on a gravel site under Federal Aviation Administration guidelines.

To further fact-check their readings, weather service staff on Wednesday measured the city’s temperature about a quarter-mile away from the official site, to a more grassy area. They observed temperatures both cooler and warmer than the official site.

“While today’s test is not the same as an in-depth study, the key takeaway: during record high temperatures [Wednesday] there is no definitive evidence that would suggest the temperature readings at [the airport] are positively biased due to sensor calibration issues or site characteristics,” the weather service determined.

From 1874 to 1928, the weather service took climate measures from different places downtown.

The weather service still records data downtown, Traphagen said. Comparing the airport gauge to the one at the Triad Center, 95 N. 300 West, temperatures are generally higher in downtown — since 1985, anyway.

Does the temperature difference matter?

Not really. If it’s hot at the airport, chances are it will still be pretty hot elsewhere in Salt Lake City, the weather service advised.

While temperatures often vary between 2 and 5 degrees from the airport’s reading across the valley, the weather service said longterm trends show valleywide warming, indicative of climate change.

Weather service data shows that Salt Lake City’s monthly mean maximum temperatures this summer have been several degrees higher than normal. July was the hottest on record at 99.7 degrees, compared to the 93.8 degree mean from 1985 to present day. The same was true in June and August.

“The temperatures, if we saw them in the heart of summer, would still be considered quite abnormally warm,” Traphagen said. “As far as the nuances of precisely how hot it gets, it doesn’t change the fact that compared to average, it’s quite warm.”

Relief is in the forecast, for this waning summer season anyway. Forecasters predict the latest high-pressure system — and heat — will have moved out of the state by this weekend.