Hermiston, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

781
FXUS66 KPDT 282233
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
333 PM PDT Sun Jun 28 2026

.KEY MESSAGES...
- Widespread breezy to locally windy conditions through this
  evening, strongest winds in the Kittitas valley

- Morning showers in eastern portions of the Columbia Basin
  tomorrow

- Below-normal temperatures, breezy to locally gusty west
  winds, and occasional light mountain showers through the week

&&

.DISCUSSION...
Water vapor satellite imagery this afternoon shows
a closed low centered along the MT/ALberta/Saskatchewan border,
which facilitated a shortwave passage over the forecast area
earlier today. Showers associated with this shortwave continue
to push south across Wallowa, Union, and Grant counties this
afternoon, with shower activity expected to diminish by early
this evening. Otherwise, a surface low strengthening under the
upper low has resulted in a tightening cross-Cascade pressure
gradient, with breezy to locally windy westerly winds (15-30 mph
with gusts 25-45mph) spilling through the Cascade gaps and into
the lower elevations. The strongest winds so far have been noted
in portions of the Kittitas valley and the Eastern Columbia
River Gorge, with gusts up to 50 mph and sustained winds around
30 mph.

Monday through Thursday: A prolonged troughing pattern
supported by periodic shortwave passages will remain over the
PacNW through the workweek. The upper low will continue to
meander east tonight through Monday, with the next round of
shower activity expected to arrive across the eastern third of
the forecast area with a shortwave passage late tonight through
tomorrow morning. There is increasing confidence (55-75%) that
showers will also impact eastern portions of the Columbia Basin
(including Tri-Cities and Hermiston) tomorrow morning, with
heaviest showers expected along the WA Blue Mountain foothills.

Cluster ensemble guidance remains in good agreement of a
shortwave trough diving down the AK/BC coastlines and across
the PacNW Tues/Wed which will bring another round of light
mountain rain showers (confidence 55-75%). Another shortwave
trough is advertised to drop into the PacNW Thursday, however,
over the last 24 hours, ensemble and deterministic guidance has
trended drier with this system. Confidence in another round of
light mountain showers for Thursday is low-mod (30-45%).

Breezy winds will remain in place across the lower elevations
and Cascade Gaps through much of the work week as the troughing
pattern persists overhead. After today, winds will generally be
between 15-25 mph with gusts up to 40 mph throughout the week.

Lastly, the persistent trough pattern will keep temperatures
much cooler than normal through the week, with afternoon
temperatures generally 5 to 15 degrees below normal (confidence
60-75%). This means that afternoon temperatures in the lower
elevations will be in the 70s, with locally 80s, throughout much
of the week. In the mountains, mid-elevations will generally be
in the upper 50s to 60s, with lower to mid 50s in the high-
elevations.

Friday and Saturday: Late Friday into Saturday, ensemble
cluster guidance is in agreement of the upper trough pushing
east, with a quasi-zonal flow and weak upper level high
pressure developing over the PacNW (confidence 40-65%). This
will result in a warming trend into near to above normal
temperatures across the forecast area (80s in the lower
elevations, 60s and 70s mountains) with dry conditions and light
winds by Saturday. Lawhorn/82

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
VFR conditions will persist through the forecast period. Winds
will continue to be be the primary concern with all TAF sites
seeing breezy conditions that range between 12-22 kts sustained
with gusts between 21-30kts.

&&

.Preliminary Point Temps/PoPs...
PDT  50  73  48  75 /  10  50  10   0
ALW  53  74  54  76 /  60  70  10   0
PSC  54  79  51  80 /  30  50  10   0
YKM  53  82  52  82 /   0  10  10   0
HRI  52  77  50  78 /   0  30  10   0
ELN  52  72  49  73 /  10  10  10   0
RDM  40  71  36  73 /   0   0   0   0
LGD  47  69  46  74 /  30  60  10  10
GCD  44  71  42  75 /   0  10  10   0
DLS  55  72  53  72 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 11 PM PDT this evening for WAZ024-026.
OR...Wind Advisory until 11 PM PDT this evening for ORZ041.

&&

$$

DISCUSSION...82
AVIATION...90