textproduct: Pocatello

KEY MESSAGES

- Mid-to-Late Week Heat Surge: Temperatures will steadily rise, reaching the low-to-upper 90s across lower valleys Thursday and Friday. Heat advisories are in effect for Thursday and Friday.

- Monsoon Moisture Returns: Models show a high pressure ridge shifting east with an approaching low system, which will bring moisture from our south back into the area. Wetter and cooler conditions will return for the weekend into next week.

- Increased Fire Danger Saturday: Models show scattered thunderstorm coverage, which will increase fire danger across the area.

DISCUSSION

Issued at 244 AM MDT Wed Aug 19 2026

Dry conditions are in store for mid-to-late week as the ridge of high pressure rebounds today, allowing southeast Idaho to warm back into above-normal territory late this week. The warming trend will continue through Friday, with widespread 90s across our lower elevations by Thursday when the high pressure ridge axis shifts directly overhead. A heat advisory is in effect for Thursday and Friday for most of our lower elevation areas.

While the details are still in flux, model ensembles show a deep PacNW low shifting the high pressure ridge eastward this weekend and opening the door for the return of monsoon moisture. The ECMWF ensemble indicates precipitation as early as Thursday afternoon while the GFS ensemble maintains dry conditions areawide until Friday afternoon.

Saturday will likely be the busiest weather day for Southeast Idaho, with scattered thunderstorms for portions of the region, but the active pattern will continue into at least the first part of the next week as low pressure remains off the coast with an area of high pressure set up over the Southwest.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 953 PM MDT Tue Aug 18 2026

Will have widespread clear skies with non impactful winds through Wednesday evening.

FIRE WEATHER

Issued at 1225 PM MDT Tue Aug 18 2026

A ridge of high pressure builds in over the area today and means temperatures begin to warm again with highs in the 80s to low 90s and min RHs generally at or below 20 percent. Winds look to remain on the lighter side during the "dry" time of Wednesday and Thursday, so we are expected to stay below Red Flag warning criteria. Models are hinting at some isolated thunderstorms returning to the higher elevations as early as Thursday afternoon, but those look VERY isolated at this point with some increasing, but still isolated activity returning on Friday as monsoon moisture returns to the area. This activity picks up as high pressure over the Four Corners region is pushed just a bit eastward by an area of low pressure moving into the Pacific Northwest.

A deep PacNW low system moves northeastward over the weekend and Saturday looks to be the most active day for our area. So, we will watch Saturday as the next best day for needing any Red Flag warnings for scattered thunderstorm coverage. Activity continues on Sunday, but appears to be a bit more isolated once again. Next week there is some disagreement on how systems will behave, but with high pressure remaining over New Mexico and Texas and troughing off the West Coast, we keep the door open for more moisture to keep working into the area each at least through Monday and Tuesday.

PIH WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon to 10 PM MDT Thursday for IDZ051- 054>057-075. Heat Advisory from noon to 10 PM MDT Friday for IDZ051>059-075.