Montana Fall 2026 Weather Forecast From the Old Farmer's Almanac

Fall officially arrives in Montana on September 22, and the Old Farmer's Almanac Fall 2026 forecast is already out with its predictions for what the next couple of months have in store. According to the Almanac, Montana is looking at a season split almost right down the middle, with eastern and western halves of the state headed in two very different directions.

Montana Fall 2026 Weather Forecast Overview

The Almanac's regional outlook ties this year's pattern to a developing El Niño, which shifts the jet stream and changes where warmth, rain and cold air travel across the country this time of year. That split shows up clearly once you break Montana down into its two forecast regions.

Eastern Montana Fall Forecast: Warmer and Wetter Than Normal

If you're in Billings or anywhere else on the eastern side of the state, you're grouped with the Northern Plains region in the Almanac's forecast, and the outlook calls for a warmer-than-normal September and October. Rainfall is also expected to come in above average, which is good news if you've been watching the drought numbers as closely as I have. A warm, wetter fall means more mileage out of patio season and a little extra help for anyone still nursing a garden through harvest.

Western Montana Fall Forecast: Cooler Conditions With More Rain

West of the Divide, the story flips. That part of the state falls under the Intermountain region in the same forecast, and it's calling for cooler-than-normal temperatures paired with above-average precipitation. If it holds, expect an earlier chill in Missoula, Kalispell and the surrounding valleys, along with more moisture moving through the mountains heading into winter.

What Montana's Fall Weather Means for Outdoor Plans

Fall is my favorite month in Montana, hands down. It's the one stretch of the calendar that doesn't ask anything extreme of you. You're not white-knuckling through a 100-degree afternoon, and you're not scraping ice off your windshield before sunrise either. The mornings turn crisp, the light gets that low golden slant across the Rims, and for a few weeks everything just feels balanced. If this year's forecast holds true for eastern Montana, we may even get to stretch that sweet spot out a little longer before the cold really sets in.

How Accurate Is the Old Farmer's Almanac Fall Forecast?

People ask me this every time one of these forecasts comes out, so I'll answer it honestly. I don't plan my life around the Almanac's predictions, but I do enjoy the tradition behind them. The Almanac has been doing this since 1792, long before satellites or radar, and there's something to be said for a publication that's stuck around that long by paying attention to solar patterns and historical weather trends. I take it the way I take most folklore, as a fun lens to look forward through, not a guarantee. Whether or not the numbers land exactly right, it gives you a reason to start thinking about flannel shirts and county fair leftovers before the leaves even start to turn.

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Montana Fall 2026 Forecast Bottom Line

Nationally, the Almanac is calling for a warmer interior and a cooler coast this fall, and Montana's split forecast fits right into that bigger pattern. For eastern Montana, plan on a mild, possibly wetter stretch through the rest of September and October. For western Montana, keep the layers handy and don't be surprised if the mountains see an early taste of winter moisture. Either way, get outside while you can. This is the season Montana does best.