Red Flag Warning 21, NWS Boise, ID

262 
WWUS85 KBOI 271212
RFWBOI

URGENT - FIRE WEATHER MESSAGE
National Weather Service Boise ID
612 AM MDT Thu Aug 27 2026

IDZ423-ORZ670>672-280200-
/O.CON.KBOI.FW.W.0021.260827T1800Z-260828T0300Z/
Owyhee Mountains-Burns BLM-Steens Mountain-Southern Grasslands-
612 AM MDT Thu Aug 27 2026 /512 AM PDT Thu Aug 27 2026/

...RED FLAG WARNING REMAINS IN EFFECT FROM NOON MDT /11 AM PDT/
TODAY TO 9 PM MDT /8 PM PDT/ THIS EVENING FOR WINDS AND LOW
RELATIVE HUMIDITIES FOR OWYHEE MOUNTAINS...BURNS BLM...STEENS
MOUNTAIN AND SOUTHERN GRASSLANDS...WHICH ARE FIRE WEATHER ZONES
423...670...671 AND 672...

* AFFECTED AREA...In Idaho, Fire Weather Zone 423 Owyhee 
  Mountains. In Oregon, Fire Weather Zones 670 Burns BLM, 671 
  Steens Mountain and 672 Southern Grasslands.

* TIMING...From noon MDT /11 AM PDT/ today to 9 PM MDT /8 PM 
  PDT/ this evening.

* WINDS...Southwest 10 to 20 mph with gusts up to 35 mph.

* RELATIVE HUMIDITY...8 to 16 percent.

* TEMPERATURES...85 to 93 degrees.

* IMPACTS...Any fire that develops will catch and spread 
  quickly. Outdoor burning is not recommended.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now, or will occur shortly.

&&

$$
W

511 
WWUS85 KBOI 280259
RFWBOI

URGENT - FIRE WEATHER MESSAGE
National Weather Service Boise ID
859 PM MDT Thu Aug 27 2026

IDZ423-ORZ670>672-280400-
/O.EXP.KBOI.FW.W.0021.000000T0000Z-260828T0300Z/
Owyhee Mountains-Burns BLM-Steens Mountain-Southern Grasslands-
859 PM MDT Thu Aug 27 2026 /759 PM PDT Thu Aug 27 2026/

...RED FLAG WARNING WILL EXPIRE AT 9 PM MDT /8 PM PDT/ THIS
EVENING FOR WINDS AND LOW RELATIVE HUMIDITY FOR OWYHEE 
MOUNTAINS...BURNS BLM...STEENS MOUNTAIN AND SOUTHERN 
GRASSLANDS...WHICH ARE FIRE WEATHER ZONES 423...670...671
AND 672...

Conditions have improved.

$$
G

Area Forecast Discussion
National Weather Service Boise ID
638 AM MDT Wed Aug 26 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Isolated afternoon thunderstorms Wednesday and Thursday,
  mainly forming over the central Idaho mountains, and southern
  Twin Falls County.

- Thunderstorms capable of producing gusty erratic outflow winds
  up to 40 mph.

- Scattered showers and isolated thunderstorms over southwest
  Idaho on Friday and Saturday capable of producing wetting
  rains.

&&

.SHORT TERM /Through Friday Night/...
Issued 334 AM MDT WED AUG 26 2026
An upper level ridge axis will remain just east of the area
through Thursday while low pressure remains situated off the
Pacific Northwest. This will keep southwest flow over the area
with above normal temperatures continuing. Breezy southwest
winds expected on Wednesday and Thursday afternoon over eastern
OR and the southwest ID highlands. Enough moisture remains over
southwest Idaho for isolated afternoon thunderstorms Wednesday
and Thursday, mainly forming over the central ID mountains, and
southern Twin Falls County. Gusty outflow winds up to 45 mph
will be the main threat with thunderstorms, most favored in the
Magic Valley and southern Twin Falls County. Tropical Storm
Iselle, just off of Baja California, is forecast to dissipate
and portions of the remnants will get ingested into the
southwest flow aloft off the CA coast and move over southwest
Idaho and extreme SE Oregon on Friday afternoon. Magic Valley
precipitable waters briefly reach the 98th percentile with this
feature so heavy rain will be a threat with storms that form
across the southwest ID highlands, central ID mountains and
southern Twin Falls County. Latest RRFS is showing more of a
stratiform rain event now, with scattered showers and isolated
thunderstorms capable of producing wetting rains (greater than
0.10 inch) over much of eastern OR and southwest ID.

&&

.LONG TERM /Saturday through Wednesday/...
Issued 334 AM MDT WED AUG 26 2026
Upper level trough over BC will continue over the long term with
below normal temperatures and a slight chance of showers and
thunderstorms. Temperatures will be near normal Saturday
before cooling to below normal Sunday as a dry cold front moves
through. Another trough digging along the BC coast will shift
the flow to southwest on Monday, and bring warmer temperatures
ahead of the next cold front. A cold front will move through the
area on Tuesday bringing cooler temperatures and below normal
temperatures Tuesday and Wednesday. Uncertainty remains elevated
in the extended period, as tropical activity in the Pacific
enhances the jet stream. Models do not handle the energy
transfer well in these situations so expect lots of changes in
the far extended period over the next week.

&&

.AVIATION /12Z Wednesday through Thursday/...
Issued 635 AM MDT WED AUG 26 2026
VFR. Isolated showers and virga during morning hours. A slight
chance of thunder. Then, isolated showers and thunderstorms
near KTWF/KJER and over central ID mtns in the afternoon/eve.
Outflows 30-45 kt. High density altitude in the afternoon due to
heat. Areas of smoke near wildfires degrading visibility.
Surface winds: E-SE 5-15 kt this morning, then mainly SW-SE
5-15 kt with gusts around 20 kt in the afternoon. Winds aloft at
10kft MSL: SW 15-25 kt.

KBOI...VFR. Isolated showers in vicinity this morning. High
density altitude in the afternoon. Surface winds: SE 5-15 kt
except turning NW 5-10kt during the afternoon.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Fire Weather Watch from Thursday afternoon through Thursday
     evening for IDZ423.
OR...Fire Weather Watch from Thursday morning through Thursday
     evening for ORZ670>672.
     Air Quality Alert until noon PDT today for ORZ062.
&&

www.weather.gov/Boise

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AVIATION.....KA
SHORT TERM...KA
LONG TERM....KA