textproduct: Boise

KEY MESSAGES

- Mostly dry with temperatures 10 to 15 degrees above normal for Memorial Day weekend.

- Gusty winds Monday ahead of a cold front, resulting in elevated fire weather conditions.

- Much cooler with gusty winds and a chance of showers and thunderstorms Tuesday and Wednesday.

SHORT TERM /Through Sunday Night/

A very stable and quiet weather pattern dominates the short term period as high pressure aloft maintains control over the Intermountain West. Clear skies and light winds will allow for efficient radiational cooling overnight, though morning lows will remain above normal. A steady warming trend will continue across southeast Oregon and southwest Idaho Saturday into Sunday as weak northwesterly flow aloft slowly transitions to a more southwesterly regime. This will increase mid level moisture along the Nevada border Saturday afternoon, aiding in CU development and potentially supporting a few isolated showers and thunderstorms (20% chance).

By Sunday, temperatures will push to around 5 to 10 degrees above seasonal normals. A strengthening surface pressure gradient ahead of an approaching Pacific low will lead to increasing westerly winds across the region Sunday afternoon, particularly through the Snake River Plain. Expect gusts to reach 20 to 30 mph by late afternoon. While a slight chance of showers and thunderstorms will exist along the Nevada/Idaho border Sunday afternoon, most of the region will remain dry through Sunday night under mostly clear skies.

LONG TERM /Monday through Friday/

The extended period begins on Memorial Day with southwest flow aloft strengthening across the region. This will push daytime high temperatures to their warmest levels of the week, topping out around 10 to 15 degrees above normal for late May. While lower elevations and valley locations will remain dry, the increased moisture and afternoon instability will support isolated showers and thunderstorms over the higher terrain of southeast Oregon and the West Central Idaho mountains Monday afternoon. Breezy to gusty conditions will develop area wide as a strong upper level trough inches closer to the coast.

A major weather pattern shift takes hold on Tuesday and Wednesday as a deep upper level trough moves inland. A strong cold front will sweep through the area, bringing a sharp drop in temperatures, widespread gusty winds, and a significantly higher chance (25% to 60%) of precipitation. High temperatures on Tuesday and Wednesday will plummet to well below normal. Widespread valley showers and high elevation mountain snow showers are expected, providing much needed moisture to the region.

The trough begins to exit the region by Thursday, allowing high pressure to slowly rebuild from the south and west. This will start a gradual drying and warming trend that carries into Friday, bringing temperatures back toward seasonal averages by the end of the work week.

AVIATION /18Z Friday through Saturday/

Issued 1122 AM MDT FRI MAY 22 2026 VFR. Surface winds: W-NW 5-15 kt, becoming variable SE less than 10 kt tonight.

KBOI...VFR. Surface winds: NW 10-15 kt, becoming SE 5-10 kt tonight.

Weekend Outlook...VFR with mostly clear skies. Winds SE or variable 5-10 kt in the nights/mornings and W-NW 5-15 kt in the afternoons. Isolated thunderstorms near the ID/NV border Sunday afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.