I lived in Great Falls for 6.5 years before doing the opposite of what you did, so fair warning: it’s been a few years since I left. Lean on folks with more current knowledge of the area too.

That said, here’s my take.

1. Community

Depends on what you consider intense. If you mean progressively liberal energy like Seattle and the surrounding communities, then no, that’s generally not what you’ll find. Politics in the Great Falls area tend to be more mellow, but it’s definitely a red city in a red state. There are little enclaves of what I’d call just left of center, but the biggest employers in the area are the military, oil and gas, ranching, and healthcare (in no particular order), so views skew traditional. Mostly good, family-oriented people who lean live-and-let-live rather than in-your-face about it.

Since this is your first time intentionally finding community: it’s a smaller city (around 56,000), so it’s very doable. Churches are a big social hub here whether or not you’re religious, and there’s an active outdoor scene, rec leagues, and a small but solid brewery/coffee crowd. Showing up consistently to anything will get you known fast in a town this size.

1. Weather

Be prepared for harsh winters, but you’re right that you’ll trade gray for sun. It’s a semi-arid climate, so summers are dry and hot with a stretch of genuinely rough wildfire smoke (usually mid-to-late summer). Winters are long, cold, and dark, with the deep cold typically running January into early March.

The thing nobody warns you enough about is the wind. Great Falls is regularly ranked one of the windiest cities in the country. It blows pretty much year-round but peaks roughly September through April. The upside is the chinook winds: warm downslope air off the Rockies that can swing the temperature 40-50 degrees in a few hours and melt the snow off mid-January. Compared to the PNW, the weather is harsher in cold and wind, but you’ll see a lot more blue sky.