Air Stagnation Advisory
URGENT - WEATHER MESSAGE
National Weather Service Boise ID
258 AM MST Tue Dec 30 2025
IDZ012-014-016-028-033-ORZ061>064-302200-
/O.EXT.KBOI.AS.Y.0005.000000T0000Z-260103T1200Z/
Lower Treasure Valley-Upper Treasure Valley-Western Magic Valley-
Camas Prairie-Upper Weiser River-Harney County-Baker County-
Malheur County-Oregon Lower Treasure Valley-
Including the cities of Corral, Malheur City, Hill City, Burns,
Dunnean, Buchanan, Baker, Caldwell, Blaine, Boise, Fruitvale,
Nyssa, Cambridge, Fairfield, New Princeton, Mesa, Crane, Twin
Falls, Venator, Council, Indian Valley, Selby, Glendale, Nampa,
Ontario, Goodrich, Diamond, and Soldier
258 AM MST Tue Dec 30 2025 /158 AM PST Tue Dec 30 2025/
...AIR STAGNATION ADVISORY NOW IN EFFECT UNTIL 5 AM MST /4 AM PST/
SATURDAY...
* WHAT...An extended period of stagnant air, with light winds and
little vertical mixing. This is due to an inversion near the
surface that will continue to trap pollutants.
* WHERE...Portions of south central and southwest Idaho and
northeast and southeast Oregon.
* WHEN...Until 5 AM MST /4 AM PST/ Saturday.
* IMPACTS...Poor air quality may cause issues for people with
respiratory problems.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Persons with respiratory illness should follow their physicians
advice for dealing with high levels of air pollution during periods
of stagnant air.
&&
$$
LC
URGENT - WEATHER MESSAGE
National Weather Service Medford OR
225 PM PST Mon Dec 29 2025
ORZ023>026-029>031-010000-
/O.CON.KMFR.AS.Y.0005.000000T0000Z-260101T0000Z/
Central Douglas County-Eastern Curry County and Josephine County-
Eastern Douglas County Foothills-Jackson County-Klamath Basin-
Northern and Eastern Klamath County and Western Lake County-
Central and Eastern Lake County-
Including the following locations...Gilchrist, Wilderville, New
Pine Creek, Steamboat, Sprague River, Butte Falls, Beatty,
Elkton, Klamath Falls, Roseburg, Rogue River, Merlin, Ashland,
Adel, Chemult, Umpqua, Drain, Grants Pass, Toketee Falls,
Glendale, Olene, Gold Hill, Paisley, Cave Junction, Jacksonville,
Applegate, Bly, Green, Winchester, Medford, Shady Cove, Lakeview,
Myrtle Creek, Crescent, Sutherlin, Valley Falls, Midland, Fort
Rock, Canyonville, and Altamont
225 PM PST Mon Dec 29 2025
...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 4 PM PST
WEDNESDAY...
* WHAT...Air quality is likely to worsen through Wednesday
afternoon. This is due to an inversion and stagnant air conditions
near the surface that will trap pollutants.
* WHERE...Valley areas, both west of the Cascades in Jackson,
Josephine and Douglas counties, and east of the Cascades in
Klamath and Lake counties.
* WHEN...Until 4 PM PST Wednesday.
* IMPACTS...Poor air quality may cause issues for people with
respiratory problems.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Persons with respiratory illness should follow their physicians
advice for dealing with high levels of air pollution during periods
of stagnant air.
&&
$$
DW
URGENT - WEATHER MESSAGE
National Weather Service Pendleton OR
1203 PM PST Mon Dec 29 2025
ORZ044-507-508-510-511-WAZ026>029-301700-
/O.NEW.KPDT.AS.Y.0002.251229T2003Z-260101T2000Z/
Lower Columbia Basin of Oregon-Foothills of the Northern Blue
Mountains of Oregon-Foothills of the Southern Blue Mountains of
Oregon-North Central Oregon-Central Oregon-Kittitas Valley-Yakima
Valley-Lower Columbia Basin of Washington-Foothills of the Blue
Mountains of Washington-
Including the cities of Madras, Naches, Ellensburg, Condon,
Pendleton, Boardman, Dufur, Heppner, Redmond, Sunnyside, Fossil,
Prosser, Dayton, Hermiston, Yakima, Waitsburg, Walla Walla,
Maupin, Moro, Athena, Ione, Prineville, Tri-Cities, Connell,
Toppenish, Pilot Rock, Thorp, and Bend
1203 PM PST Mon Dec 29 2025
...AIR STAGNATION ADVISORY IN EFFECT UNTIL NOON PST THURSDAY...
* WHAT...Stagnant conditions will have the potential to trap
pollutants near the ground and deteriorate air quality.
* WHERE...Foothills of the Blue Mountains of Oregon and Washington,
Lower Columbia Basin of Oregon and Washington, North Central
Oregon, Central Oregon, Kittitas Valley, and Yakima Valley.
* WHEN...Until noon PST Thursday.
* IMPACTS...Periods of air stagnation can lead to the buildup of
pollutants near the surface, potentially leading to poor air
quality.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
An Air Stagnation Advisory indicates that due to limited movement of
an air mass across the advisory area, pollution has the potential to
increase to dangerous levels. Persons with respiratory illness
should follow their physicians advice for dealing with high levels
of air pollution during periods of stagnant air, state air quality
agencies highly recommend that no outdoor burning occur and that
residential wood burning devices be limited as much as possible.
According to state air quality agencies, prolonged periods of
stagnant air can hold pollutants close to the ground, where people
live and breathe. Check with your local burn agency for any current
restrictions in your area.
&&
$$
MC
URGENT - WEATHER MESSAGE
National Weather Service Missoula MT
1123 AM PST Mon Dec 29 2025
IDZ005>008-012000-
/O.NEW.KMSO.AS.Y.0002.251229T2000Z-260101T2000Z/
Northern Clearwater Mountains-Southern Clearwater Mountains-
Orofino/Grangeville Region-Lower Hells Canyon/Salmon River Region-
1123 AM PST Mon Dec 29 2025
...AIR STAGNATION ADVISORY IN EFFECT UNTIL NOON PST THURSDAY...
* WHAT...Stagnation conditions will trap pollutants, leading to
deteriorating air quality.
* WHERE...Lower Hells Canyon/Salmon River Region,
Orofino/Grangeville Region, Southern Clearwater Mountains, and
Northern Clearwater Mountains.
* WHEN...Until noon PST Thursday.
* IMPACTS...Periods of air stagnation can lead to the build up of
pollutants near the surface.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Persons with respiratory illness should follow their physicians
advice for dealing with high levels of air pollution during periods
of stagnant air.
According to state air quality agencies, prolonged period of
stagnant air can hold pollutants close to the ground where people
live and breathe. Check with your local burn agency for any current
restrictions in your area.
&&
$$
