textproduct: Pocatello

KEY MESSAGES

- Near-Record Heat Today: Unseasonably warm October weather continues today with valley highs in the lower-to-mid 80s. Isolated afternoon showers or storms in the South Hills and along the Montana Divide could produce gusty winds, though most areas stay dry.

- Continued Warm Mid-Week: The southern ridge gets suppressed slightly Tuesday through Friday, cooling highs by a few degrees while remaining 10 to 15 degrees above normal under zonal flow aloft

- Breezy Saturday Transition: Winds will increase on Saturday as the regional pressure gradient tightens ahead of an approaching Pacific Northwest trough, holding highs in the 60s and 70s.

- Drastic Cooldown & Rain/Snow (SundayEarly Next Week): High confidence in a major fall pattern shift Sunday and Monday, bringing a sharp temperature drop, rain, mountain snow, and even the potential for valley snow flakes depending on the final evolution of the system

DISCUSSION

Issued at 106 PM MDT Mon Oct 5 2026

An unusually warm October weather pattern remains firmly established across eastern Idaho today. Afternoon satellite imagery displays mid-to-high level cloudiness drifting overhead, but near-record to record high temperatures are still expected as lower-elevation valleys climb into the lower-to-mid 80s. High-resolution convective-allowing models (CAMs) indicate a low-end chance for an isolated shower or thunderstorm to develop later this afternoon across the South Hills or along the Montana Divide. While atmospheric moisture is limitedkeeping precipitation accumulation minimalpassing cells will be capable of generating localized gusty downdraft winds. The vast majority of eastern Idaho will remain dry and unseasonably hot.

The upper-level ridge anchored to our south gets suppressed on Tuesday as 500 mb heights dip slightly across the Intermountain West. In response, daytime maximum temperatures will drop a few degrees Tuesday through Friday under a predominantly zonal flow regime. Despite this minor temperature reduction, afternoon highs will continue to run 10 to 15 degrees above seasonal climatological norms. Dry conditions and light-to-moderate surface winds will prevail through the end of the workweek.

Weather conditions begin to transition on Saturday as global guidance tracks a potent upper-level low digging into the Pacific Northwest. As the regional pressure gradient tightens ahead of the approaching trough, surface winds will increase markedly across the Snake Plain and higher terrain. Increased cloud shading and wind mixing will cap Saturday high temperatures in the 60s and 70s. While these readings remain slightly above seasonal averages, Saturday marks the leading edge of a significant airmass change.

Confidence continues to increase in a drastic cooldown arriving Sunday and extending into early next week as the parent upper low crosses the region. While ensemble guidance exhibits ongoing spread regarding the exact depth and track of the system, significant cold advection, widespread precipitation, and elevated winds appear increasingly likely. Current National Blend of Models (NBM) thermal guidance appears to sit on the warm side of latest model runs, suggesting daily high temperatures may trend even lower in upcoming forecast cycles. High-elevation mountain snow is looking increasingly probable Sunday night into Monday, with guidance indicating a non-zero possibility for valley snow flakes depending on how rapidly cold air fills in behind the front. Additionally, valley frost/freeze conditions appear possible for early next week. Forecast details will be refined over the coming days as guidance converges, but a definitive shift toward true fall weather is on the horizon.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1043 AM MDT Mon Oct 5 2026

Overall minimal impacts expected. There is a very slight chance of some convective activity and have vicinity overnight at BYI and SUN but low confidence in occurring on site. Winds generally remain light and mostly under 10 knots through Tuesday morning.

FIRE WEATHER

Issued at 106 PM MDT Mon Oct 5 2026

Trend through Friday remains very hot with dry conditions with minimum humidity in the 15 to 25 percent range and highs in the 70s and 80s for the most part. Generally 15 to 20 degrees above normal for the high temperatures. There remains a very slight chance of convective activity late today and tonight into Tuesday mainly in zones 427, 413, 422 and 476 but very low confidence in any precipitation. Winds not forecast to be very strong this week through Thursday with some high elevation 15 to 25 mph gusts the highest. Will see a pattern change Friday into the weekend with winds increasing Friday and Saturday ahead of an upper level trof and surface cold front which may bring some much needed precipitation Sunday into next Monday with much cooler temperatures.

PIH WATCHES/WARNINGS/ADVISORIES

None.