textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated showers and thunderstorms are expected this afternoon and evening, and again on Friday, near the Idaho- Nevada border.

- Dry through the weekend, with slight chances of thunderstorms returning early next week. - Steady warming trend into the weekend, with the hottest temperatures expected Sunday through Wednesday.

SHORT TERM /Through Saturday Night/

Issued 335 AM MDT THU JUL 2 2026 Broad troughiness is in place over the Northwest this morning, with a band of moisture aloft oriented across south-central Idaho per water vapor imagery. This area coincidentally will be the only area to see isolated thunderstorm development today, primarily along the Idaho/Nevada border south of I-84 this afternoon and evening. This scenario is likely to repeat in nearly identical fashion again on Friday, as little change to the upper air pattern occurs. Elsewhere, general air mass drying has occurred over the past 24 hours, with precipitable water values roughly around 0.5 inch, which is slightly below normal for the date, keeping the thunderstorm threat spatially confined.

The other impact will be the continued warming trend amidst midlevel height rises, with high temperatures generally in the 80s today in the lower elevations, but rising another 10 degrees by Saturday. Humidity values will also bottom out in the 10-15 percent range in most areas Friday and Saturday.

For the 4th of July, all indications are that the preceding drying trend will lead to a quiet holiday across the entire area, in stark contrast to last year which saw much more active weather. However, with the building heat, HeatRisk levels will approach moderate across much of the I-84 corridor. Precautions should be taken for extended periods of outdoor activities on Saturday, especially for those sensitive to heat.

LONG TERM /Sunday through Thursday/

Issued 335 AM MDT THU JUL 2 2026 The extended period will mark the onset of persistent warm, summer-like conditions, as heat across the eastern half of the US finally expands westward into the Intermountain West. While temperatures will be 5-10 degrees above normal, more extreme heat will be mitigated by persistent southwesterly flow aloft along the Pacific coast, which will keep the building upper ridge somewhat suppressed to the south. Nevertheless, high temperatures in the mid-upper 90s are likely Sunday through Tuesday, continuing widespread moderate HeatRisk impacts each day.

Monsoonal moisture will also advect northward early next week and bring a return of a slight chance of thunderstorms Monday through Wednesday. An uptick in afternoon breeziness will also occur early next week, especially across southern Idaho.

AVIATION /12Z Thursday through Friday/

Issued 551 AM MDT THU JUL 2 2026 VFR. Isolated showers/thunderstorms returning along the ID/NV border near KTWF Thursday afternoon. Surface winds: W-NW 5-10 kt. Becoming light and variable overnight. Winds aloft at 10kft MSL: W-SW 10-20 kt.

KBOI...VFR with mostly clear skies. Surface winds: NW 6-11 kt. Light and variable overnight.

Weekend Outlook...VFR with dry conditions and intermittent clouds.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.