021
FXUS65 KFGZ 181037
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
337 AM MST Tue Aug 18 2026

.SYNOPSIS...Temperatures warm up to 5-10 degrees above average
throughout the week. Low grade monsoon conditions continue today
with only isolated storms over the White Mountains. By midweek,
thunderstorm coverage begins to increase across the area as more
moisture is drawn into the state.

&&

.DISCUSSION...High pressure over the state will keep the region in
low grade monsoon conditions today. Only the White Mountains and
parts of the Rim are expected to see any activity. High temperatures
under this feature will warm to 5-10 degrees above average and
stay there most of the week. An Extreme Heat Warning has been
issued for areas below 4,000ft in the Grand Canyon from Tuesday
morning and lasting through Thursday night, so use caution if you
hike below the Grand Canyon Rim.

By midweek the high pressure area shifts to the east and centers
over the Four Corners which is more conducive for monsoon moisture
to overspread the state. Look for POPs to rise across the higher
terrain starting Wednesday and by Thursday or Friday most of the
area should see a chance of showers/storms. Increased moisture
and cloud cover by this weekend should get temperatures back down
to seasonal averages. As storm coverage increases and soils once
again become wet, flash flood concerns will be on the rise late
this week and into the weekend.

&&

.AVIATION...Tuesday 18/12Z through Wednesday 19/12Z...VFR conditions,
brief MVFR near showers/storms. Scattered showers/storms in the
White Mountains, with isolated showers/storms possible over the
Rim between 18Z-03Z. Daytime winds SW-W 5-10kts, light and
variable or terrain driven overnight. Gusty and erratic winds
possible near storms.

OUTLOOK...Wednesday 19/12Z through Friday 21/12Z...VFR conditions,
brief MVFR near showers/storms. Isolated to scattered showers/storms
over Rim and White Mountains Wednesday between 18Z-03Z. Scattered
showers/storms Thursday starting on the high terrain and spreading
into lower elevations by late afternoon/early evening. Winds SW-W
5-15kts daytime Wednesday, W-NW 5-15kts daytime Thursday, light
and variable or terrain driven overnight. Gusty and erratic winds
possible near storms.

&&

.FIRE WEATHER...Today and Wednesday...Temperatures rise to 5-10
degrees above average. Expect isolated to scattered showers and
thunderstorms each day with the best coverage over the eastern
Mogollon Rim and White Mountains. Winds SW-W 5-10 mph each day,
gusty and erratic winds possible near storms. Minimum RH values
10-15% over the lower deserts to 30-35% in the White Mountains.

Thursday through Saturday...Temperatures 5-10 degrees above average
Thursday, 5 degrees above average Friday, cooling to near normal
over the weekend. Scattered showers and thunderstorms increasing in
coverage each day with most of the area seeing a chance for
shower/storms by the weekend. Winds W-NW 5-15 mph Thursday, S-SW 5-
15 mph Friday and Saturday. Gusty and erratic winds possible near
storms.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM this morning to 8 PM MST
Thursday for AZZ006.

&&

$$

PUBLIC...Bernhart
AVIATION...Bernhart
FIRE WEATHER...Bernhart

For Northern Arizona weather information visit
weather.gov/flagstaff