textproduct: Salt Lake City

KEY MESSAGES, Issued 928 AM MDT Tue Aug 18 2026

- Building high pressure will bring a steady warming trend in temperatures as conditions dry, bringing a threat of isolated critical fire weather conditions.

- Monsoon moisture will move back into Utah and southwest Wyoming late in the week, persisting through at least early next week. This will bring an increased threat of showers and thunderstorms capable of producing flash flooding.

DISCUSSION, Issued 928 AM MDT Tue Aug 18 2026

High pressure is centered near the Utah/Nevada border this morning with some shortwave energy rippling over the top of it. Thus, seeing clear skies except for southwest Wyoming and areas near the Utah/Idaho border. Satellite derived PWs indicate values primarily in the 0.7 to 1.0 inch range, enough moisture for some afternoon convective development. Coverage should be generally isolated in nature, with the best coverage over northeastern portions of the area, closer to the upper jet associated with the passing shortwave energy.

Under the influence of the ridge, high temperatures today will be similar to yesterday with maxes near seasonal normals. With the ridge expected to amplify and move overhead Wednesday into Thursday, temperatures will steadily warm, with maxes averaging up to 10F above seasonal normals by Thursday, with the greatest departure from normal over northern portions of the area. The airmass will dry out during this time, with relative humidities approaching critical values for portions of western Utah. Locally breezy conditions could bring a few pockets of critical fire weather conditions, but overall the threat is quite isolated. HeatRisk values are forecast to move into the red (major) range for some northern Utah valleys on Thursday, including the west desert and parts of the Wasatch Front. Overall, though, the increased threat of heat related illness will be mitigated due to overall acclimation during the season.

By Friday, there is high confidence that the ridge will move its axis to the monsoon favored position over the Four Corners, drawing deep moisture back northward and increasing the potential of showers and thunderstorms capable of producing flash flooding. This will also remove the threat of critical fire weather conditions and bring temperatures back to near normal for this time of year. The monsoon moisture is expected to remain in place through at least early next week.

AVIATION

KSLC...WNW to NW winds up to around 10 kts expected to hold through around 04Z Wednesday, shifting SE thereafter through the night. VFR conditions to prevail with SCT to BKN clouds largely above 10 kft.

REST OF UTAH AND SOUTHWEST WYOMING...In SW WY and far NE UT, some isolated showers and thunderstorms will develop through Tuesday afternoon. At other area terminals, anticipate diurnally normal wind shifts with light magnitudes generally less than 10 kts, and a mix of cloud cover largely above 10 kft.

FIRE WEATHER, Issued 435 AM MDT Tue Aug 18 2026

Hot and dry conditions continue through the work week as high pressure gradually strengthens across the region. Conditions remain critically dry across lower elevations through this period. A slight uptick in afternoon winds today will result in elevated to locally critical fire weather conditions developing mainly across lower elevations of central and southern Utah. Otherwise, the main concern remains the threat for isolated afternoon showers and thunderstorms capable of producing dry lightning and gusty and erratic outflow winds. An influx of monsoonal moisture is expected Friday onward across the region, with storms trending wetter through the weekend as a result.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.