Spring: March 15 - June 15
The days become noticeably longer here in Southwest Montana with the beginning of daylight savings time around Easter. Early spring warm spells get the locals off the ski hills and onto the rivers in search of rising trout on just about every river in the area. For many anglers, this is their favorite time of the year as rising fish aren't too wary and can be easy to find on cloudy days. Midges and Blue Winged Olives are the primary hatches during early spring, but the Mother's Day Caddis hatch is what everyone is hoping to hit just before the runoff starts in early May.
The Mother's Day Caddis hatch consistently offers some of the best dry fly fishing of the year on the Yellowstone and Madison Rivers. Timing is everything with this hatch, as the rivers will be blown out if you're too late. We encourage people to shoot for the last week of April through early May as fishing will be great even if the caddis aren't out yet.
The weather in late April is typically beautiful with daytime temperatures in the 70's and nights near freezing. The last 2 weeks of April and first week of May is one of the real “sleeper” times of year around Southwest Montana as the crowds of summer are still months away, the fish feed actively throughout the day, and the scenery is spectacular.
Once the spring melt really gets going, the larger rivers reach flows up to 10X the summer flows. We focus our attentions on the spring creeks of Paradise Valley, private reservoirs, and regional tailwaters such as the Missouri and Big Horn during the height of spring runoff. Although the options can be limited during this time of year, we're always able to find some good conditions within a short drive of Bozeman and the persistent angler can come away with some great memories.
Runoff conditions vary from year to year, but we usually see dropping river flows in early June and fishable conditions soon follow. As the rivers begin to drop, stonefly nymphs begin their migration to the banks and the trout follow them. Nymphing with giant stonefly nymphs and dead-drifted streamers while the rivers are still high and dirty can be really productive. We usually see some dry fly fishing on Salmonflies in early June, but the height of the hatch typically begins around mid June on the Upper Madison and Yellowstone Rivers.
During May and June, daytime temperatures are usually mild and thundershowers are very common. The surrounding landscape is bright green thanks to the melting snow and spring showers. The river bottoms offer refuge to a multitude of wildlife species as they rear their young and it's common to see everything from baby otters to nests filled with fledgling Ospreys. In addition to some great fishing, late spring is one of those times of year when the crowds aren't too bad and the weather is usually very comfortable all day long.