textproduct: Pocatello

KEY MESSAGES

- Mid-Week Heat Peak: A building high-pressure ridge will drive a strong warming trend through Wednesday. Expect valley temperatures to climb into the upper 80s to lower 90s, with mountain locations reaching the upper 70s and mid-80s.

- Elevated Fire Danger All Week: Afternoon relative humidity will plunge into the 15% to 25% range across the workweek. Combined with an uptick in dry thunderstorm potential mid-week and accelerating winds by Thursday and Friday, fire weather concerns remain highly elevated.

- Drastic Weekend Pattern Shift: An unusually deep, early- summer low-pressure system will track inland for the weekend. This system will trigger a dramatic 15 to 20-degree drop in temperatures, deliver widespread wetting rain, and maintain elevated winds through early next week.

DISCUSSION

Issued at 235 AM MDT Tue Jun 23 2026

Gradual rises in H5 heights are expected over the next few days as a high-pressure ridge subtly amplifies over the Intermountain West. This synoptic configuration will maintain a distinct warming trend across eastern Idaho. Today and Wednesday are shaping up to be the thermal peaks of the week, though ambient temperatures will remain above seasonal normal levels through Friday. Expect daytime highs to max out in the upper 80s to lower 90s across valley floors, while higher elevation zones top out in the upper 70s to mid-80s. A minor compaction of H5 heights may allow mountain locations to cool down by just a few degrees on Thursday and Friday. Widespread fire weather concerns will remain elevated through the week as afternoon relative humidity minimums bottom out between 15% and 25% across the majority of the region.

The upper-level flow will turn more volatile late in the week. A passing shortwave embedded within the larger zonal flow will bring breezy down-valley winds on Thursday. Winds are progged to accelerate further on Friday as the surface pressure gradient rapidly sharpens ahead of an unusually deep, early-summer low- pressure system tracking toward the Pacific Northwest.

By Saturday and continuing into early next week, the core of this potent low will move directly overhead, triggering a dramatic downward plunge in temperatures that will drop readings 10 to 20 degrees below seasonal normal levels. Widespread wetting rainfall is expected across much of eastern Idaho, which will heavily suppress localized fire weather concerns. Afternoon maximums will struggle to escape the 60s across valley floors from Saturday through Monday, while the high country remains locked in the 50s. While this pattern shift will provide excellent overnight relative humidity recoveries, the tight packing of the gradient will ensure that ambient winds remain elevated through the weekend and into the first part of next week.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1011 PM MDT Mon Jun 22 2026

Mainly clear skies overnight and tomorrow with a bit of an increase in mid and high level cloud cover Tuesday afternoon. Winds are not expected to get much more than 10 knots Tuesday afternoon at all TAF sites. No aviation impacts expected through Tuesday.

PIH WATCHES/WARNINGS/ADVISORIES

None.