844
FNUS75 KBOI 281829
FWSBOI

Spot Forecast for Big Grass Fire...USFS
National Weather Service Boise ID
1229 PM MDT Tue Jul 28 2026

Forecast is based on forecast start time of 1800 MDT on July 28.
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.

...HOT, DRY, AND BREEZY AFTERNOON WINDS TODAY THROUGH FRIDAY...
...DRY FRONTAL PASSAGE LIKELY SATURDAY/SUNDAY FOR INCREASED WINDS...

.DISCUSSION...
Used a forecast point near between Jim Peaks and South Mountain
Idaho which looked more representative for fire. High pressure
will continue hot, dry, and breezy conditions over the into the
weekend. Generally diurnally driven winds which look to be
predominately from the south-southwest. Wind gusts up to 20 mph on
the ridgetops during the afternoon. Poor RH recoveries expected
each night. Dry frontal passage for Saturday looks bring increased
west-northwest winds into Sunday. About a 40% chance of critical
winds and RH`s for an RFW.

.TONIGHT...

Sky/weather.........Partly cloudy.
Min temperature.....61 to 66.
Max humidity........41 to 51 percent.
CWR.................0 percent.
Wind - 20 foot......Southwest 7 to 12 mph. Gusts up to 18 mph in the
                    evening.
Mixing height.......100 ft AGL.
Transport winds.....North around 10 mph.

.WEDNESDAY...

Sky/weather.........Mostly sunny.
Max temperature.....90 to 96.
Min humidity........10 to 15 percent.
CWR.................0 percent.
Wind - 20 foot......Southwest 5 to 9 mph. Gusts up to 14 mph in the
                    afternoon.
Mixing height.......10500 ft AGL.
Transport winds.....Southwest around 10 mph.

.WEDNESDAY NIGHT...

Sky/weather.........Partly cloudy.
Min temperature.....59 to 64.
Max humidity........42 to 48 percent.
CWR.................0 percent.
Wind - 20 foot......South 5 to 8 mph with gusts to around 16 mph in
                    the evening shifting to the southeast 3 to 9
                    mph overnight.
Mixing height.......100 ft AGL.
Transport winds.....South around 5 mph.

$$
Forecaster...Smith
Requested by...Matt Brown FBAN
Type of request...WILDFIRE
.TAG 2618438.2/BOI
.DELDT 07/28/26
.FormatterVersion 2.0.0
.EMAIL matt.brown@sccfd.org