Nampa, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

056
FXUS65 KBOI 261118
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
518 AM MDT Tue May 26 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Rain and high elevation snow across southeast Oregon today,
  with thunderstorms this afternoon and evening across the
  southwest Idaho mountains.

- Much cooler today with gusts 30-45 mph developing by this
  evening.

- Additional showers and thunderstorms and periods of gusty
  winds Wednesday through Sunday.

- Thunderstorms may produce gusty winds 40-60 mph and blowing
  dust, brief heavy rain, and hail this week.

&&

.SHORT TERM /Through Thursday Night/...
Issued 308 AM MDT TUE MAY 26 2026
An upper low will bring active weather to the area through much
of the short term. The low, located over southwest Oregon this
morning, will slowly shift south and then stall over northern
California and western Nevada through mid week. It will be much
cooler today in eastern Oregon today (20-30 degrees cooler) due
to the proximity of the low, but cooling will be less
pronounced in southwest Idaho (10-20 degrees cooler). Rain and
high elevation snow above 5500-7000 feet will increase this
morning across Harney County Oregon closer to the low center,
then expand across southeast Oregon and far southwest Idaho
this afternoon.

Meanwhile, instability will increase this afternoon and evening
in the warm sector across the southwest Idaho mountains. A
surface low and shortwave trough rotating around the upper low
will aid lift for shower and thunderstorm development. Storms
will move north-northwest this evening and are favored to
remain over the mountains, with about a 20% chance of a
thunderstorm drifting west over the Treasure Valley.
Thunderstorms may produce brief heavy rain, small hail, and
gusty outflow winds 40-60 mph which may produce blowing dust.
Showers will also expand in coverage this evening outside of
thunderstorms. Precipitation amounts of 0.25-0.50" through
tonight are expected in Harney County, locally up to 1", with
lower amounts elsewhere. Rainfall amounts from thunderstorms
will be highly variable, but up to 1" will be possible from the
strongest storms. Outside of thunderstorms, expect gusty
northwest winds, strongest this evening with gusts 30-45 mph
owing to a tight pressure gradient across the area.

As the low stalls Wednesday and Thursday, south to southeasterly
flow across the area will bring around 10 degrees of warming
from Tuesday, with the coolest temperatures persisting along the
Oregon/Nevada border. Moisture will continue to rotate around
the low, bringing periodic chances of showers and thunderstorms.
The highest chance will be across southeast Oregon, as well as
each afternoon and evening across the mountains of southwest
Idaho as daytime heating increases instability. Warmer surface
temperatures will support more instability than today, and there
will be enough shear for localized stronger thunderstorms
capable of producing gusty outflow winds and hail. Outside of
storms, expect gusty southeast winds, strongest across southern
areas each afternoon with gusts 20-40 mph.

&&

.LONG TERM /Friday through Tuesday/...
Issued 308 AM MDT TUE MAY 26 2026
Active weather will continue to end the week. A trough digging
down the coast of British Columbia will steer the filling low,
that`s been stagnant over the Great Basin, northward over our
area. As this low lifts, showers will continue to make
themselves known through Friday and Saturday. Ensembles continue
to resolve sufficient instability building in, with surface
heading and height falls aloft, to support a threat of
thunderstorms come Friday afternoon. Come Saturday, the greatest
precipitation chances (50-85%, increasing as you move
northeast) will be over the West Central Mountains. While
instability will be weak, mountain thunderstorms Saturday
afternoon can`t be ruled out. The shortwave will also give way
to breezy conditions to end the week.

Guidance hints at a weak shortwave, associated with the
aforementioned trough, crossing over our area Sunday. However, a
dry slot will limit moisture availability, limiting slight
precipitation chances to higher terrain. Temperatures through
the weekend will generally be at or leaning below normal. As the
shortwave exits our area late Sunday/early Monday, a building
ridge will support a warming trend to start next week. By
Tuesday, temperatures will be up to around 10 degrees above
normal.

&&

.AVIATION /12Z Tuesday through Wednesday/...
Issued 518 AM MDT TUE MAY 26 2026

Generally VFR. Scattered showers continuing throughout the day,
expanding in coverage this afternoon. Thunderstorms developing
across central ID this afternoon, capable of small hail, and
outflows to 20-40 kt. Ceilings lowering to MVFR near KBKE/KBNO
this afternoon. Precip tapering off early Wed/AM. Surface winds
outside of storms: SW-NW 5-15 kt this morning, increasing to
10-20 kt with gusts to 20-35 kt this afternoon. Winds aloft at
10kft MSL: S-SW 10-30 kt.


KBOI...VFR. Occasional weak showers/virga this morning, with
erratic outflows possible. Scattered showers this afternoon
with a 20% chance of lightning. Surface winds: NW 8-12 kt this
morning, then NW 15-20 kt with gusts to 25-30 kt this afternoon.


&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.

OR...None.

&&

$$

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AVIATION.....NF
SHORT TERM...ST
LONG TERM....NF