St. George, Utah 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

249
FXUS65 KSLC 200402
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1002 PM MDT Wed Aug 19 2026

.KEY MESSAGES...

- Building high pressure will bring a steady warming trend in
  temperatures through Thursday across the south and through
  Friday across the north.

- 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...High pressure centered over AZ this evening will
shift east on Thursday before ending up over NM/west TX over the
weekend where it is expected to remain in place into early next
week. This shift will initially aid in a continued warming trend
before bringing increased moisture into the area beginning during
the Thursday/Friday timeframe. Current PWATs of around 0.8 inches
is expected to increase to 1-1.1 inches across the area by
Saturday afternoon.

Expect afternoon highs of near to above 100 degrees in many
valleys on Thursday even as midlevel moisture starts to creep into
southern Utah. On Friday, as the moisture starts to surge into
southern and central Utah, temperatures there may begin to cool
but continue to trend slightly warmer or at least remaining near
persistence across northern Utah. This moisture, the initial surge
being associated with a vort max lifting through the area, will
then spread into northern Utah by Saturday, allowing for a cooling
trend thereafter. HeatRisk is in the Red (Major) category across
many valley areas on Thursday, then will become more confined to
northern Utah for Friday. Heat Advisories are in effect for west-
central through northwest Utah valleys as a result. The need for
any Warnings is diminished due to acclimation to hot temperatures
throughout the summer.

With the arrival of the moisture, expect increasing coverage of
showers and thunderstorms along with increasing heavy rain
potential into early next week. There is currently a Marginal Risk
of Excessive Rainfall across southern Utah Thursday and Friday.
This Marginal Risk will spread through the rest of the forecast
area for Saturday and Sunday.

The high pressure looks to slowly start building westward again by
the middle of next week. Depending on how for west the high center
ends up (as there is still some model spread in this regard), the
airmass may start to gradually dry for the second half of next
week.

&&

.AVIATION...KSLC...The SLC terminal will see VFR conditions through
the overnight hours with some high clouds. Light and variable winds
will become prevailing southerly by 05Z and should shift to the
northwest again between 18Z and 20Z.

REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR
conditions with generally light and terrain driven winds through the
overnight hours. Isolated showers and thunderstorms are expected to
develop over eastern Utah tomorrow afternoon before dissipating
tomorrow evening. Any storms that develop will be capable of
producing gusty and erratic thunderstorms winds, lightning, and
brief mountain obscurations.

&&

.FIRE WEATHER, Issued 131 PM MDT Wed Aug 19 2026...
Strengthening high pressure will continue to bring a
trend of warming and drying across Utah, with high temperatures
in many lower lying valley areas reaching back into the triple
digits. Alongside the heat, further drying is expected across
Utah`s West Desert on Thursday with humidity falling by another 5
percent. As such, isolated pockets of single digit humidity are
expected in the West Desert on Thursday afternoon. On a positive
note, winds will remain generally light and terrain driven through
the heat and low relative humidity, keeping significant fire
weather concerns low. High-based moisture will make a subtle
increase on Thursday, bringing increased coverage of dry
thunderstorms over Utah`s high terrain. Still, coverage is
expected to be isolated to widely scattered.

Moisture continues to increase through the late week and into the
weekend, bringing increased coverage of showers and thunderstorms
across Utah. With increasing lower level moisture, the potential
for wetting rains from individual storms will greatly increase. In
addition to the increasing chances for wetting rains, afternoon
relative humidity will also significantly improve throughout the
mountainous terrain while RH values in the lower elevation valleys
of western and eastern Utah will struggle to rise out of the
teens.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory from noon Thursday to 7 AM MDT Saturday for
     UTZ101>106.

     Heat Advisory from noon Thursday to 7 AM MDT Friday for UTZ115-
     116.

WY...None.
&&

$$

PUBLIC...Cheng
AVIATION...Traphagan
FIRE WEATHER...Webber

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity