Temperatures forecast to hit 104°F will compound already unhealthy air quality across the Wasatch Front starting Friday, creating a dual public safety threat for Cottonwood Heights and Holladay residents.

The National Weather Service has issued an Extreme Heat Warning for the Salt Lake City area, including Cottonwood Heights and Holladay, from noon Friday, Aug. 7 through midnight Monday, Aug. 10. Forecasters expect highs near 104°F on both Friday and Saturday, with overnight lows dropping only into the 70s and 80s.

That lack of nighttime cooling is what makes this stretch dangerous. When bodies can't recover overnight, the risk of heat exhaustion and heat stroke climbs sharply.

Salt Lake City already tied its all-time August record of 105°F on Aug. 2, according to KUTV.

Smoke still hanging over the valley

The heat arrives on top of wildfire smoke that has blanketed the area for days. As we reported Aug. 3, ash and haze from the Widemouth Fire and blazes in Nevada and the Pacific Northwest have settled across the Salt Lake Valley.

Holladay was specifically named in the EPA's AirNow readings as being in the "Unhealthy for Sensitive Groups" category, according to ABC4. That designation means children, older adults, pregnant people and anyone with asthma, heart disease or diabetes should limit time outdoors.

ABC4 meteorologist Cedric Haynes wrote in an Aug. 5 forecast that the heat risk is rising to "major and extreme categories for most valley areas" as the high-pressure ridge strengthens over Utah through the weekend.

What residents should do

Dr. Angela Allen, an emergency medicine physician at Intermountain Medical Center, said July 10 when a prior heat warning was issued that "extreme heat can be one of the deadliest weather hazards in the United States." She urged residents to learn the difference between heat exhaustion and heat stroke: confusion or altered mental status signals heat stroke, which requires an immediate 911 call.

Salt Lake County's Cool Zones program provides air-conditioned space at county recreation centers. The nearest location to Cottonwood Heights and Holladay is Dimple Dell Recreation Center, 10670 S. 1000 East, Sandy. Salt Lake County Mayor Jenny Wilson's office expanded Cool Zone hours during the Aug. 2 heat event; residents should check slco.to/zones for updated hours during the Aug. 7–10 warning period.

The county has urged residents to check on neighbors, especially older adults, young children and people who work outdoors.

Some relief possible by Sunday

The high-pressure ridge is expected to shift east by Sunday, Aug. 9, opening the door for monsoonal moisture that could bring showers and a few degrees of cooling. Forecasters note that any rain over burn scars carries a flash-flood risk, though the probability remains low through Saturday.