The Missoula area has good fishing across most of the year, but what's best changes a lot depending on the season — and on what kind of trip you're after.
Spring (April–June): This is runoff season, when melting snow can turn rivers high, fast, and muddy — not great for wading, though some years the timing works out well for float trips. The big exception is Rock Creek's famous salmonfly hatch, usually in late May or June, when big bugs bring big trout to the surface and it's one of the most popular weeks of the year to fish there.
Summer (July–August): This is peak season for most rivers, with warm weather and steady, fishable flows. One thing worth knowing: during hot, dry stretches, Montana Fish, Wildlife & Parks sometimes puts "hoot-owl" restrictions in place on certain rivers — afternoon closures (roughly 2 p.m. to midnight) meant to protect trout when water gets too warm. These come and go depending on that summer's conditions, so if you're planning a summer trip, it's worth checking FWP's current restrictions page before you go.
Fall (September–October): Many serious anglers call this the best season of all. Water cools back down, crowds thin out, and fish feed heavily to prepare for winter. It's a great time on the rivers, and lake fishing on Flathead Lake stays strong too.
Winter (November–March): Flathead Lake runs trolling charters nearly year-round, including through the winter, and Georgetown Lake is a solid pick for guided ice fishing. Salmon Lake and Seeley Lake also see plenty of DIY ice fishing action, though most anglers there go out on their own rather than with a guide.
Whatever time of year you're planning around, there's a way to fish near Missoula that fits it. From here, take a look at where to fish, how to pick a guide, or compare local outfitters for your trip. You can also head back to the fishing hub any time.