Salt Lake City recorded its highest temperature in 152 years on July 12, when the mercury reached 109 degrees Fahrenheit. The National Weather Service confirmed the milestone, which shatters a long-standing record of 107 degrees that had been set in 1960, 2002, 2021, and twice during 2022.
Breaking a Century-Old Record
The National Weather Service Salt Lake City reported on social media that the 109-degree peak was observed at approximately 2:58 PM MDT. This temperature represents a new all-time high for the area since record-keeping began at the site in 1874.
According to official weather observations from Salt Lake City International Airport, the extreme heat was accompanied by low humidity levels. During the period of peak temperature, the relative humidity dropped as low as 5%, with a heat index reaching 101 degrees Fahrenheit.
Atmospheric Drivers of Heat
The record-breaking heat is driven by a strong ridge of high pressure centered over southern California that has been moving eastward. In a forecast discussion issued on July 10, the National Weather Service noted that this feature had already caused temperatures to trend upward, averaging 5 to 8 degrees above seasonal normals.
The atmospheric conditions have created an anomalously strong high-pressure system overhead, creating near-record temperatures and very dry conditions, particularly across northern Utah. This heat has also contributed to unstable conditions in the atmosphere during afternoon hours.
Regional Temperature Threats
While Salt Lake City saw its all-time record broken, other parts of the region faced similar threats to their temperature records. The National Weather Service indicated on July 10 that Logan had a 75 percent chance of surpassing its all-time record high of 103 degrees Fahrenheit, while Evanston, Wyoming, had over a 60 percent chance of breaking its record of 95 degrees Fahrenheit.
An extreme heat warning was in effect for several Utah zones, including those covering areas with temperatures potentially reaching between 108 and 121 degrees Fahrenheit. The warning for these specific zones was scheduled to remain in place until 6 AM MDT on Tuesday.
Public Health Precautions
The heatwave is expected to persist through the weekend and into early next week. Forecasters warned that the intense temperatures bring a significantly increased risk of heat-related illnesses for the general population in most valley and mountain valley locations.
To mitigate these risks, the National Weather Service advised those with outdoor activities to move them away from the hottest parts of the day whenever possible. Officials emphasized that staying hydrated and remaining indoors in cooled areas is the most effective way to prevent heat-related illnesses.
Incoming Monsoonal Moisture
As the heatwave continues, a shift in weather patterns is expected to introduce monsoonal moisture into the region. By Sunday night, the center of the high-pressure ridge is expected to move east of the area, placing Utah and southwest Wyoming under a southerly flow aloft.
This change will begin advecting monsoonal moisture from the south starting as early as Sunday night. While this may bring increased cloud cover, it also introduces an elevated threat of flash flooding, particularly across southern Utah, where convection is expected to develop by Monday afternoon.
Long-Term Forecast Outlook
Looking further into the week, weather officials expect the moisture tap to expand northward. By mid-week, while the increase in moisture may be limited by variable winds between weather features, the existing high levels of moisture will likely remain in place.
This persistent moisture, combined with the heat, maintains the risk for convection and flash flooding across much of the forecast area through the upcoming week.
