San Tan Valley, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

742
FXUS65 KPSR 200525
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1025 PM MST Thu Jun 19 2025

.UPDATE...Updated 06z Aviation Discussion.

&&

.KEY MESSAGES...

- Extreme Heat Warnings remain in effect across south-central
  Arizona through tomorrow as lower desert high temperatures
  range from 108 to 116 degrees.

- Very dry and increasingly breezy conditions will lead to
  elevated to locally critical fire weather conditions across
  higher terrain areas of south-central Arizona on Friday and
  Saturday.

- A cooling trend through the weekend will lead to below normal
  temperatures by Sunday, persisting into next week.

&&

.DISCUSSION...
Dry and unseasonably hot conditions continue today as the Desert
Southwest remains under the influence of the strong subtropical
ridge of high pressure. Early afternoon objective analysis shows the
ridge axis over New Mexico with 500 mb heights around 591-593 dm
across our area. Temperatures this afternoon are expected to be the
hottest of the week as a few areas are anticipated to eclipse 115
degrees for the first time this year. Major HeatRisk is in place
today across much of south-central Arizona where an Extreme Heat
Warning remains in effect through Friday evening. Folks should
exercise the necessary heat safety precautions to avoid any heat-
related illnesses.

Meanwhile, satellite WV imagery this afternoon shows a Pacific
trough beginning to push into the Pacific Northwest. This will lead
to decreasing heights across the region as the trough moves inland
and displaces the ridge to the east. Temperatures begin to
decrease starting Friday with the cooling trend continuing into
the weekend. Forecast highs Friday fall to around 106-110 degrees
across the lower deserts before dropping below normal for the
weekend. By Sunday, temperatures may struggle to get into the
triple digits for some lower desert locales. Thus, the Moderate
and Major HeatRisk we`ve seen this week will be replaced with
widespread Minor HeatRisk this weekend. Cooler than normal
temperatures will continue into next week as the aforementioned
troughing feature persists over the region. Aside from the cooler
temperatures, we will see increasing winds across the region over
the next couple of days in response to the approaching trough.
Afternoon wind gusts Friday and Saturday are expected to climb to
upwards of 20-30 mph with locally higher gusts across the higher
terrain east of Phoenix into southern Gila County as well as
across western portions of Imperial County. Ensemble guidance
indicates gusts around 40 mph will be possible across western
Imperial County, particularly on Saturday, so a Wind Advisory
could be needed in future updates. The strong winds combined with
very dry conditions will lead to elevated to locally critical fire
weather concerns, especially across the southern Gila County
higher terrain.

.PREVIOUS DISCUSSION...
Global ensemble members continue to show a battle between dry air
and more moist monsoon moisture over our CWA early next week. Models
have shifted this slightly to be more of a Tuesday-Wednesday
timeframe rather than Monday-Tuesday. The aforementioned Pacific
trough will work to keep dry air and southwesterly flow in place, at
least over SE CA and western AZ. But, some deep moisture over
northern Mexico looks to make its way into SE AZ. This moisture, in
combination with upper-level support, could lead to some isolated to
scattered thunderstorms. This supports some low end chances for
showers and storms as far north as the White Mountains and into Gila
County.

&&

.AVIATION...Updated at 0530Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Trends in winds will be the main weather issue through Friday
evening under clear skies. Westerly component winds this evening
will return to easterly direction during the overnight hours.
Anticipating another early afternoon switch to the west, although
there may be a few hours of cross-component or variability in
directions and speeds during this transition period. Afternoon
gustiness expected to pick up once again 20-25 kts prior to
subsiding during the evening hours tomorrow.

Southeast California/Southwest Arizona including KIPL and KBLH:
Periodic gusty winds will be the main weather concern through
Friday afternoon under clear skies. Wind speeds should relax
overnight with directions potentially become somewhat variable
around sunrise ahead of another round of afternoon gusty winds at
both terminals. Afternoon/early evening gusts tomorrow should
hover in the 25-30 kt range. Some reduced visibilities in haze due
to a distant wildfire is possible at IPL tomorrow evening should a
SW component wind push the smoke plume into the Imperial Valley.

&&

.FIRE WEATHER...
Hot and dry conditions will continue today with winds following
their typical diurnal patterns with some occasional afternoon
breeziness gusting upwards of 15-25 mph. A few gusts in excess of
30 mph will be possible this evening across western portions of
Imperial County. Winds further increase across the region Friday
and Saturday with afternoon gusts climbing to upwards of 20-30
mph. The strongest gusts will remain focused across the higher
terrain north and east of Phoenix and across western portions of
Imperial County, where gusts may exceed 30 mph. Min RHs through
Friday will be around 5-10% before climbing to around 10-15% on
Saturday. The dry conditions combined with the gusty winds will
lead to elevated to locally critical fire weather conditions.
Extreme heat conditions will continue through Friday across much
of south-central Arizona with lower desert highs Friday ranging
between 106-110 degrees. Elevated fire weather concerns will
subside going into early next week as winds weaken and temperatures
continue to cool to around or just below normal while also
increasing MinRHs into the teens.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Friday for AZZ534-537>544-
     546>556-559>562.

CA...None.
&&

$$

DISCUSSION...Smith
PREVIOUS DISCUSSION...Berislavich
AVIATION...Young
FIRE WEATHER...Smith/Berislavich