textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Widespread frost and areas of freezing temperatures late tonight into Saturday morning.

- Frost likely in lower valleys Sunday and Monday mornings.

- Remaining unsettled through the weekend and into early next week. Temperatures will gradually warm toward normal by mid week.

SHORT TERM /Through Sunday Night/

Issued 219 PM MDT FRI APR 24 2026 The region remains under the influence of a cool northwest flow as a large upper low sits over western Canada. This will continue isolated rain and snow showers across the central Idaho mountains through this evening. For tonight, clear skies and light winds will allow for efficient radiational cooling. Temperatures across most of the Treasure Valley and western Magic Valley are expected (greater than 80% chance) to drop below freezing. A Freeze Warning remains in effect for these areas for Saturday morning.

On Saturday, a Pacific low pressure system begins moving inland from California into the Great Basin, bringing a slightly warmer and more moist air mass. This will increase moisture and instability over the higher terrain for showers, especially along the Nevada border. The lower valleys will see mostly dry conditions on Saturday. By Sunday and Monday, the upper level low weakens into an open trough as it continues east across the southern Great Basin. This persistent unsettled pattern will maintain low chances for afternoon mountain rain and snow showers. A slight chance (15% chance) of thunderstorms along the Nevada border is possible especially on Sunday afternoon as the trough moves through.

Cold overnight temperatures will continue to be a concern for sensitive vegetation Sunday and Monday mornings. While Sunday and Monday may stay just warm enough to avoid a widespread freeze, a Frost Advisory for the Treasure and Western Magic Valleys will likely (80% chance) be needed as lows dip between 32 to 36 degrees. Temperatures through the period will remain 5 to 10 degrees below seasonal normals.

LONG TERM /Monday through Friday/

Issued 219 PM MDT FRI APR 24 2026 A trough extending from a low centered over Canada will continue to linger over the region, bringing high terrain showers (30-50% chance) on Monday and Tuesday and temperatures about 5-10 degrees below normal. Showers will generally be light, with minimal accumulation. Snow levels will stay around 5000-6000 feet, dipping down to 4500 feet overnight Monday into Tuesday. High pressure will then move into the region late Tuesday, bringing a warming trend through the end of the long term period. Temperatures will reach about 5-10 degrees above normal, with about a 10% chance that the Treasure Valley will hit 80F. Lingering mountain showers are possible through Thursday with this warming trend, but forecast confidence is low (10% chance).

AVIATION /00Z Saturday through Sunday/

Issued 530 PM MDT FRI APR 24 2026 VFR with scattered cumulus clouds mainly over higher terrain this evening. Mostly clear skies overnight through Saturday morning. Scattered mountain snow showers returning tomorrow afternoon near KMYL and KBKE. Surface winds: W-NW 10-20 kt, with gusts up to 35 kt over Magic Valley, until sunset. Variable less than 10 kt overnight. Winds aloft at 10kft MSL: NW 10-25 kt shifting to SW 10-20 kt after Sat/12Z.

KBOI...VFR. Surface winds: NW 10-15 kt, calming to variable less than 6 kt tonight after 03Z.

Weekend Outlook...Generally VFR with localized MVFR-IFR conditions in isolated showers over high terrain each afternoon. Low confidence of thunderstorms (10-20% chance) near the NV border each afternoon. Mountains obscured in precipitation. Surface winds: variable 10 kt or less Saturday, W-NW 5-15 kt Sunday with gusts to 25 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Freeze Warning from midnight tonight to 9 AM MDT Saturday for IDZ012-014-016. OR...Freeze Warning from midnight MDT /11 PM PDT/ tonight to 9 AM MDT /8 AM PDT/ Saturday for ORZ064.