textproduct: Boise

KEY MESSAGES

- Dry with temperatures averaging 10 to 15 degrees above normal through next week.

- Sunday is expected to be the warmest day, when highs may approach or exceed daily records.

- A minor disturbance on Monday will bring a low chance of showers and thunderstorms to higher terrain along the Nevada border and across central Idaho.

SHORT TERM /Through Sunday Night/

An expansive upper level ridge will gradually amplify and shift east today through the weekend, becoming centered near the Four Corners region by Sunday. The ridge will bring warm and dry conditions to our area today and Saturday, with high temperatures 10 to 15 degrees above normal. Even warmer temperatures will arrive Sunday as the ridge reaches peak strength with an subtle uptick in southerly flow aloft. Temperatures will approach record highs in some locations, including Boise, where the forecast high of 89 degrees will threaten the daily record of 88. Additionally, there is a 40% chance that the high could reach 90 degrees in Boise, which has not occurred in the month of October since 2015. High clouds will rotate around the ridge and move overhead today, but mostly clear skies are expected over the weekend. High clouds will then increase Sunday night ahead of a weak shortwave trough. Winds will be light through the period.

LONG TERM /Monday through Friday/

A weak shortwave trough will move across the area on Monday and weaken the ridge, cooling temperatures by a few degrees but overall remaining well above normal. While moisture will be limited, there will be enough for a 5 to 10% chance of showers and thunderstorms across the higher terrain along the Nevada border and central Idaho.

As the trough departs, the ridge will rebuild to our south Tuesday through Thursday. This will keep clear, warm, and dry conditions in place. However, systems moving by well to our north dampen the ridge slightly with temperatures not quite as warm as Sunday and Monday. On Friday, an upper level trough will approach the Pacific Northwest. Temperatures are expected to remain warm through Friday with cooler temperatures and precipitation not arriving until the weekend, but confidence on the timing of this system is lower. Additionally, some models (particularly the GFS/GEFS) indicate potential for tropical moisture ahead of Hurricane Rachel (currently south of the Baja California peninsula) to move into the West, but confidence on any impacts in our area from this possible outcome is very low.

AVIATION /06Z Friday through Saturday/

Issued 1133 PM MDT THU OCT 1 2026 VFR with increasing high clouds through Friday morning. Areas of thin smoke layers aloft/haze at the surface, mainly north of KBNO and near KMYL. Patchy fog in sheltered mountain valleys in the morning. Surface winds: variable or SE under 7 kt overnight through Friday morning, then W-NW 5-10 kt in the afternoon. Winds aloft at 10kft MSL: W-SW 10-20 kt.

KBOI...VFR with mostly clear skies. Surface winds: SE or variable under 7 kt through the morning, becoming NW 5-10 kt in the afternoon.

Weekend Outlook...VFR with mostly clear skies Saturday through Sunday. Potential for thin smoke layers aloft and haze at the surface due to prescribed burns in the region, mainly over southeast OR and west-central ID. Surface winds: variable up to 10 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.