As we wrap up August, a cool, wet stretch is in the forecast, bringing our first real taste of fall to Yellowstone. This week’s rain will likely bring muddy water conditions back to the Lamar River and Soda Butte Creek in the Northeast Corner, while cooler, wetter weather puts the brakes on terrestrial fishing for the moment, while prompting our first round of fall hatches.

Update: Yellowstone lifts full closures for Firehole, Madison and Gibbon rivers

Effective Friday, Aug. 28, anglers can fish the Firehole, Madison and Gibbon (downstream of Norris Campground) rivers and all associated tributaries from sunrise until 2 p.m. each day. Cooling weather and water temperatures, as well as precipitation in the current weather forecast, allow for the full closures to be lifted.

The full closures were implemented on July 15 because low water flows and high water temperatures exceeding 68 degrees Fahrenheit (20 degrees Celsius) can be lethal to fish. Water temperatures have cooled at night, allowing for fishing for part of the day. Anglers can fish on most other park rivers, streams and lakes daily from sunrise to sunset as specified in the 2026 Fishing Regulations booklet.

Staff will continue to monitor the water temperatures. Temporary restrictions may be lifted, or additional closures may be put in place, depending on condition assessments.

Anglers: Please fish during the coolest times of day and land fish quickly. Do not play hooked trout to exhaustion. Gently handle fish in the water as much as possible and let them recover before release. Your cooperation will protect the park’s fisheries and may prevent the need to prohibit fishing at all times of the day on some rivers and streams if conditions worsen. 

Keep an eye on Park closures HERE for the latest updates.

HERE'S THIS WEEK'S STANDOUTS. 

SLOUGH CREEK

Slough Creek will remain clear, and a good option during the upcoming week. With cooler temps in the forecast, don't expect much action until late morning, and be prepared to fish small (size#18-22) Baetis mayfly patterns like Sparkle Duns, or Kellers Cripple BWO. 

Emergences of fall drakes (Timpanoga hecuba) are possible from here on out through the fall on Slough Creek, and this week’s cool, cloudy weather could provide the perfect conditions for the first good hatches of these big size #12 mayflies. Keep an eye out for drakes beginning to emerge in the late-morning and afternoon, especially on the coolest, cloudiest days.

Dry-dropper rigs with a small beadhead below an ant or small hopper can be productive too. 

GALLATIN RIVER (in YNP)

The Gallatin River inside YNP has fished well this summer, and with a change in conditions coming, you can expect that good fishing to continue, just in a different gear. Fish will continue looking for hoppers as long as the sun and warm weather hold, but once the rain and cooler temperatures arrive, be ready to shift tactics and look for afternoon hatches of Baetis mayflies.

On the coldest days, emergences may not get going until late in the afternoon, and the biggest fish will often rise subtly in sneaky spots. An extra dose of patience and persistence may be required, but these conditions should produce some fun, albeit technical, dry-fly opportunities.

SODA BUTTE CREEK & LAMAR RIVER

Take advantage of the last day or two of warm, dry weather before the weekend. Terrestrial fishing should remain a solid option while conditions hold, but water clarity will likely deteriorate on these two Northeast Corner cutthroat trout gems once the heavier rain arrives.

Keep a close eye on Lamar River flows HERE. A sharp bump in flows is usually a good indication that muddy water is working its way through the system. As always, give us a call at 406-646-7801 or stop by the shop for the latest conditions.

YELLOWSTONE RIVER

The lower canyon reaches of the Yellowstone will likely get off-color below the Lamar once the rain arrives this weekend. However, sections of the canyon above the Lamar confluence, along with the upper Caldera stretch, should remain clear and fishable.

In the Caldera, targets are becoming more limited as Yellowstone Cutthroat begin returning to the lake, but there are still some good fish in the system if you’re willing to cover ground to find them.

Cloudy conditions will make sight-fishing difficult in the coming week, so take advantage of any sunny windows you get. When the clouds and rain roll in, shift your attention to hatches of Baetis (size #18–22) and possibly Heptagenia mayflies (size #16–18). These cooler, overcast conditions can produce some surprisingly good late-summer dry-fly fishing when the bugs show up.

As always, check in with the shop for the latest conditions, fly recommendations, and river updates. We’re here to help you stay dialed in for your next adventure!