Heat in Arizona, May 21, 2026

Area Forecast Discussion
National Weather Service Tucson AZ
143 AM MST Thu May 21 2026

.SYNOPSIS...Dry and warm conditions for the remainder of the
week with the exception of today's afternoon breezes. Another
weather system will be moving into the region by the late weekend,
bringing slight chances for rain showers and thunderstorms
especially on Monday.

&&

.DISCUSSION...
The upper air pattern has a general troughiness pattern over the
western United States. There is a low pressure circulation
pulling away from the tip of the trough axis over southern
California. This low will track to the southeast, below Arizona,
starting later today and into the weekend. As it does that,
areas along the International Border and in Cochise County will
experience southwesterly breezes with gusts up up 25 mph.

Friday and into Sunday...Southeast Arizona will generally be in
a benign pattern as the low passes to the south of the state. It
will bring mid-to-upper level moisture into the region, leading
to less than 5-10% chances for rain showers in the afternoons,
but generally it will be a few cloud build ups and possibly
virga over the higher terrain. Temperatures will rise 1-2
degrees each day and staying near normal for this time of year.

Monday and into the new week...Another low pressure center will
move into the region, bringing better moisture. PWATs will be
between 0.6 to 0.7 inches by Monday. Thus, chances for rain
showers and thunderstorms be increasing late Sunday to early
Monday. Monday afternoon has the better chances for thunderstorm
and rain shower development due to higher instability from the
surface heating and some upper air dynamics with the low. Right
now, chances for development are still around 15-30% with the
higher terrain having the better chances. Winds will also start
to pick up as the low moves over Arizona on Monday and into
Tuesday. Ensemble models are trending towards a continuation of
breezes through the new week due to a trough from the northwest
plunging into the Great Basin, and gobbling up the low pressure
center.

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.AVIATION...valid through 22/12Z.
SCT-BKN clouds AOA 20K feet AGL east of KTUS with SKC to the
west this early morning becoming generally SKC wide by 21/15Z
with the occasional passing high cirrus. SFC winds SELY/SLY
less than 10 kts this morning and again after 22/03Z. By 21/18Z,
SWLY/WLY at 10-15 kts with gusts up to 20-25 kts this
afternoon. the strongest of winds will be between KALK to KDUG.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...
Dry conditions will continue through the remainder of the work
week before mid-level moisture moves into the region by the
weekend. Winds will generally be less than 15 mph through
Sunday with the exception for Cochise county today with winds
around 15 mph with strong gusts. Min relative humidities will be
sitting in the teens to the mid-20s. Mid to upper level
moisture will approach as early as this weekend south and east
of Tucson. Enough moisture to produce daily afternoon cloud
build ups starting as early on Friday. More impactful moisture
will likely move in on Monday as another weather system moves
through. There is a 10 to 30 percent chance of showers and
thunderstorms Monday mainly from Tucson eastward, with lingering
non-zero precipitation chances mainly in the White Mountains on
Tuesday. Breezes will tick up Monday and Tuesday to around 15
mph and lasting through the most of the new week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.

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