Hermiston, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

330
FXUS66 KPDT 200502
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1002 PM PDT Wed Aug 19 2026

.KEY MESSAGES...
- Dry and warm weather through Friday.

- Low pressure will approach the region on Friday and will move
  inland late Friday night or early Saturday, bring shower and
  thunderstorm chances, mainly to the mountains and gusty winds.

- Fire weather conditions look to become elevated, if not
  critical as we approach the weekend.

&&

.DISCUSSION...
Southwesterly flow will remain over the Pacific Northwest
as the region remains between a large area of high pressure
over the four corners and low pressure over the Pacific Ocean.

Heights will rise over the area through Friday and temperatures
are expected to rise into the mid to upper 90s both Thursday and
Friday. HeatRisk values will be widespread moderate on Thursday
with some local Major Risk. The usual caveats apply to
temperatures. The presence of wildfire smoke will affect
afternoon high as it has for much of the summer, and clouds
should be increasing on Friday, as the offshore low approaches,
which could also temper the high temperatures.

The low in the Pacific will move northeastward towards the
Washington and Oregon coasts through Friday. It will then move
onshore with late Friday night ore early Saturday as an open
trough, before continuing northeastward into British Columbia.

Latest guidance has trended slower with the motion of the low,
an most of Friday now appears dry. There could be some
showers/thunderstorms over far western sections of the area
during the afternoon, but most of the precipitation chances look
to occur during the evening/overnight hours on Friday and then
Saturday looks to be the better day for shower or thunderstorm
potential, mainly in the mountains. Right now, chances remain
about 15 to 20 percent for thunderstorms, while shower chances
are higher (30-40 percent), especially over the Oregon Cascades
Friday evening/night and Washington Cascades on Friday
night/Saturday.

Additionally, as the trough moves and associated cold front
moves across, winds will increase on Saturday and become gust,
with wind gusts 25 to 35 mph possibly as high as 45 mph in the
normally breezier locations...the Kittitas Valley, Simcoe
Highlands, Columbia Basin, Gorge and Foothills of the Blue
Mountains. In these areas NBM probabilities of wind gusts >=39
mph range from 50 to >90 percent. Wind gust probabilities >=47
mph range from 10 to over 60 percent locally.

The strong winds will meet with marginal RH values that will be
marginal for Red Flag Warning criteria. Will continue to
monitor this, and conditions will be elevated, but confidence is
not high enough that they will reach critical levels.

Beyond Saturday, we get into a drier west to eventually
southwest flow.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
VFR conditions perisit through the forecast period. Winds will
be generally light under 12 kts. There is low confidence
(10-15%) in smoke making it to the surface and reducing VIS to
5SM or MVFR conditions.

&&

.FIRE WEATHER...
Dry conditions with low relative humidity is expected through
Friday. Then, an area of low pressure will approach the region
and move onshore late Friday night or early Saturday. This low
could touch off some showers and thunderstorms, mainly over
western areas in the afternoon on Friday, but the better (yet
still low (<20 percent) chances of thunderstorms look to be
Friday night and Saturday over the mountains.

Additionally, as the low and associated cold front moves
northeastward, winds will increase across the region, gusty
west winds will develop on Saturday. Winds could gust 25 to 35
mph, with gusts possibly as high as 40 to 45 mph especially
across the Kittitas Valley, Simcoe Highlands, Columbia Basin,
Gorge and Foothills of the Blue Mountains. RH values will rise
with the frontal passage. Fire weather conditions will be
elevated and could become critical on Saturday, but RH values
currently are marginal.

&&

.Preliminary Point Temps/PoPs...
PDT  56  95  62  95 /   0   0   0   0
ALW  64  97  67  99 /   0   0   0   0
PSC  56  97  61  99 /   0   0   0   0
YKM  61  98  65  98 /   0   0   0   0
HRI  59  97  64  97 /   0   0   0   0
ELN  60  94  64  95 /   0   0   0   0
RDM  50  96  56  94 /   0   0   0   0
LGD  57  98  61 100 /   0   0   0   0
GCD  57  98  61 100 /   0   0   0   0
DLS  62  99  67  96 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...Air Quality Alert until 11 AM PDT Thursday for ORZ050-502-505-
     506-509>511.

&&

$$

DISCUSSION...77
AVIATION...90
FIRE WEATHER...77