932
FNUS75 KBOI 081854
FWSBOI

Spot Forecast for Big Grass...BLM...UPDATED
National Weather Service Boise ID
1254 PM MDT Tue Sep 8 2026

Forecast is based on forecast start time of 1800 MDT on September 08.
If conditions become unrepresentative...contact the National Weather
Service.

Please contact our office at (208)334-9060, if you have questions
or concerns with this forecast.

...WARMING AND DRYING THROUGH THURSDAY...
...BREEZY WINDS THURSDAY AFTERNOON THROUGH SATURDAY...

.DISCUSSION...
High pressure over the area will bring mostly clear skies,
warmer than normal temperatures, and light diurnal winds later
today through Wednesday. A mostly dry low pressure system will
arrive Thursday through the weekend, bringing gusty west winds and
a cooldown while keeping the burn area dry. Thursday afternoon
will start seeing elevated wind breezes with gusts over 20 mph.

.TONIGHT...

Sky/weather.........Mostly clear.
Min temperature.....45 to 51.
Max humidity........55 to 65 percent.
CWR.................0 percent.
Wind - 20 foot......North-northeast 5 to 10 mph, becoming
southeast and downslope around 6 mph after
midnight.
Mixing height.......100 ft AGL.
Transport winds.....Southeast around 5 mph.
Ventilation Index...5 poor.

.WEDNESDAY...

Sky/weather.........Sunny.
Max temperature.....79 to 85.
Min humidity........15 to 21 percent.
CWR.................0 percent.
Wind - 20 foot......Southeast up to 6 mph in the morning
shifting to the west-northwest 5 to 8 mph in
the afternoon.
Mixing height.......6000 ft AGL.
Transport winds.....West around 10 mph.
Ventilation Index...600 good.

.WEDNESDAY NIGHT...

Sky/weather.........Mostly clear.
Min temperature.....53 to 58.
Max humidity........36 to 42 percent.
CWR.................0 percent.
Wind - 20 foot......Northwest-north up to 6 mph in the evening
shifting to the southeast and downslope 3 to 8
mph overnight.
Mixing height.......100 ft AGL.
Transport winds.....Southeast around 5 mph.
Ventilation Index...5 poor.

.THURSDAY...

Sky/weather.........Mostly sunny.
Max temperature.....83 to 89.
Min humidity........15 to 23 percent.
CWR.................0 percent.
Wind - 20 foot......Southeast 3 to 8 mph in the morning shifting to
                    the west 10 to 15 mph with gusts to around 24
                    mph in the afternoon.
Mixing height.......8000 ft AGL.
Transport winds.....West around 20 mph.
Ventilation Index...1600 excellent.

$$
Forecaster...Yang
Requested by...Alicia Schlarb
Type of request...WILDFIRE
.TAG 2621344.2/BOI
.DELDT 09/08/26
.FormatterVersion 2.0.0
.EMAIL 2026.biggrass.plans@firenet.gov