Introduction to Fly Fishing Montana in Late Spring

Fly fishing Montana in late spring (mid-May through June) can be great or it can be terrible. It all depends on if you’re fishing the right places or not.

This period brings the spring runoff season in Montana and Yellowstone Park, the beginning of summer hatches on many warmer rivers as well as all lakes, the opening of the Yellowstone Park fishing season, and the beginning of tourist season. At the start of this period there are only a handful of fishing opportunities, though those that are fishable at this time are generally at or near their yearly best, but more and more rivers and lakes become fishable as June progresses, and the consistency of the fishing generally improves as time goes by.

Late spring is an excellent time for those who wish to visit Yellowstone Park during the “peak” season but keep away from the worst crowds, as well as those who wish to fish the Missouri River. It is also an excellent period on almost all lakes, with most seeing their best dry fly fishing of the year during calm weather in June. The Lower Madison River also offers excellent fishing, though it’s usually rather crowded.

On the other hand, it’s important to bear in mind that many rivers are almost always out of play until at least the last week of the month, and often even into July. These include the Yellowstone and Lamar Rivers, which are always too muddy in the first half of the month and usually still muddy until at least the 25th. Some stretches of the Yellowstone are also closed until mid-July, as are several less-important fisheries.

Weather and Water Conditions

Late May is typically wet and cool, while June usually features quite pleasant weather, but it has greater swings than July and August see. In late May and even early June it is common to see quite a bit of cold rain and one or two snowstorms even at low elevations, though it is unlikely to stick save on the highest peaks. By late June, daytime temperatures often reach 85-90 degrees at low elevation, but nights are typically quite cool. Rain is common in June at all elevations, particularly early in the month.

In sum, anglers visiting in late spring must still be prepared for cold weather, but it’s the exception rather than the rule, and after the middle of June you’ll be able to fish most locations most days wearing just pants and a shirt, though it’s still a good idea to have a light jacket in addition to the ever-important rain coat.

Water conditions are highly variable in late spring. Large freestone rivers, particularly the Yellowstone and its tributaries, including the Boulder and Stillwater in Montana and the Lamar System and Gardner inside Yellowstone Park, typically see peak runoff near the beginning of June, then slowly recede through the month.

Lower-elevation streams are usually out of runoff by mid-June, and those with geothermal (geyser) inputs experience short runoff periods and are usually fishable sometime between the Memorial Day weekend opener in Yellowstone Park and June 10, depending on how much snow fell the previous winter and how quickly it melted in early May. The high water period on tailwater rivers usually ends by mid-June, after water managers can be sure that the upstream reservoirs will not reach maximum capacity. Note that tailwaters get high, but not muddy, so they remain fishable through runoff. Lakes are generally at their highest in June, whether these are small natural ponds at high elevations in Yellowstone Park or large man-made reservoirs. This doesn’t hurt the “catching,” in fact June offers the best fishing of the year on most lakes, but it can make approaching the lakes on foot treacherous, with muddy and marshy shores and uncertain footing.

All waters drop and clear as late spring progresses. On rivers like the Yellowstone, this is a good thing. On geothermal streams like the Firehole, it’s a bad thing: these rivers (particularly the Firehole) often begin to get too warm sometime in the last ten days of the month. On tailwater rivers: it’s a more ambivalent development. The dry fly fishing improves as the water drops, but the nymph fishing gets harder, the fish get spookier, and the rivers start to get weedier.

Top Fisheries

Yellowstone Park opens to fishing the Saturday of Memorial Day weekend, and the handful of rivers and lakes inside the park that are out of their runoff enough to be fishable at this time are top draws for many anglers fly fishing Montana in late spring. The best and really only bet most years at the beginning of the season is the Firehole River, while the Madison, Gibbon and lower Gardner can also be fishable. All of these rivers except the Gardner get better over the next week or two. The Gardner stays so-so at best until about June 20 most years. The Madison and Gibbon stay good through June, and the Gardner is actually at its best in high summer, but the Firehole can get chancy in the last ten days of the month, particularly in low water years.

In dry years, portions of the Yellowstone River near Tower Falls can be exceptional after June 10, but most years the Yellowstone and all its tributaries except one or two tiny creeks and the Gardner River remain too high and muddy through at least June 25 except during brief “runoff breaks.”

Runoff breaks occur when several days of cool but dry weather slow the runoff enough for rivers to drop and clear to a sort of gray-green color. These breaks are impossible to plan for, but offer the best fly fishing in Montana in late spring when they occur. The Boulder River enjoys such breaks more often than the larger Yellowstone does, and the Tower Falls area in the lower Grand Canyon of the Yellowstone is more likely to enjoy them than other stretches of the Yellowstone inside or outside the park.

Most lakes in Yellowstone Park can be fishable right out of the gate, but some remain closed and many hike-in lakes are hard to approach due to snow and marshy conditions. Most lakes get much better from mid-June until the end of the month, as the water begins to drop and they get easier to approach.

Outside the park, the Yellowstone remains out of play until June 15 even in the driest years except during the aforementioned runoff breaks. Average years see it drop into high but fishable shape by the last week of June, while wet years this is more likely July 5-10. The Boulder usually comes into play a few days earlier. The Lower Madison is exceptional through June, though morning fishing is much better than afternoon fishing late in the month, particularly in dry years. The Missouri is good throughout this period, with the fishing gradually transitioning from mostly nymphing early in the month to dries later. Spring creeks are usually poor in the first half of this period, since hatches are limited, but the world-famous Pale Morning Dun hatches which offer the best dry fly fishing of the year on these waters begin sometime in mid-late June. Lakes outside the park are usually very good in June, including both private ranch lakes and many public reservoirs.

Inside Yellowstone Park, my favorite fisheries at this time are the Gibbon River Canyon and assorted small lakes, particularly those that host grayling. During the rare low-water years when the Grand Canyon of the Yellowstone is low and clear enough to fish during this period, it jumps to the head of the list. Outside the park, I like private ranch lakes, the Lower Madison River, the Land of Giants stretch of the Missouri River, and the Boulder and Yellowstone if runoff breaks occur.

Fishing Tactics

While the year’s first consistent dry fly fishing gets underway during this period, nymphs and wet flies remain the most productive options when fly fishing Montana in late spring. Dries gradually get more important everywhere as the period progresses. In dry years, the upper Madison River right on the edge of Yellowstone Country Fly Fishing’s operations area and even the Yellowstone can see its Salmonfly hatches begin sometime between the 15th and 20th of June, but the last few days of June extending into mid-July is more likely.

Early on, mayfly nymphs are good choices on any rivers that are more clear than brown, while on dirtier and higher rivers like the Gardner and Boulder (when clear), stonefly and large attractor nymphs are better. These same nymphs continue to work through the month. Dry mayfly fishing focuses on BWO and PMD on the Firehole early in the period and PMD on other clear rivers as the period progresses. The Lower Madison also holds a few Gray Drakes.

Caddis (including caddis dries) are important on the Firehole, upper Madison in Yellowstone Park, Lower Madison, and Missouri throughout this period. Soft hackles are particularly good matches for emerging caddis on the Firehole, but they work everywhere these insects are hatching. The caddis fishing is probably best on the Firehole and on the Lower Madison during this period. The Lower Madison often enjoys two or three solid weeks of Mother’s Day caddis hatches from mid-May into early June, with tan caddis taking over thereafter.

Large attractor and stonefly dries work sporadically on portions of the Firehole and Upper Madison in Yellowstone Park, and may kick in on the Yellowstone inside and outside the park as well as elsewhere on the Madison late in June if runoff ends at an early or normal time. Classic attractor dry/dropper combinations work well on the Gibbon River by June 10, as well as a few small streams that start becoming fishable around June 20.

On lakes, leeches, San Juan Worms, and soft hackle wet flies imitating emerging midges are the bread and butter flies, but Callibaetis mayfly imitations (nymphs and dries) and large dry midges also work. Some ranch lakes also see good damselfly hatches, though these are rare.

Here’s a fishing tip that applies from now through September: Don’t hesitate to fish dry flies even if you don’t see trout rising. This will be unexpected advice particularly for anglers used to fishing eastern tailwaters. With the warmer water and abundant surface food common during the core of the season here, it is not at all uncommon to find the fish more willing to eat dries than nymphs. The steeper, smaller, and rougher the stream, the more likely you can fish dries all or most of the time. Even portions of the Yellowstone River fall into this category. You are less likely to be able to stick to dries on spring creeks, tailwaters, and lakes.

Who Should Consider Fly Fishing Montana in Late Spring?

Fly fishing Montana in late spring is a good choice for those who wish to fish in generally comfortable conditions but avoid the heaviest crowds, which are usually present from July through September. It is also a good time for those looking to fish the Missouri and Madison Rivers in a general sense, as well as anglers interested in private lakes. It’s also THE time to fish the Firehole River–it’s almost always the period that offers the best fishing of the season on this river.

This is not a good period except in EXCEPTIONALLY dry years for those eager to fish the Yellowstone or Boulder River and is NEVER a good period to fish the Lamar River or its tributaries Slough and Soda Butte Creek. These bodies of water are essentially never good in June, and are usually completely unfishable until at least June 25 and often much later. Anglers eager to fish spring creeks need to come at the tail end of this period, after PMD hatches get going. This is also a poor period for anglers looking to fish on foot who are not physically fit, since the footing is usually tough due to high water and unsteady banks at this time, even on waters that are more-or-less done with their spring runoff. In addition, crowds are bigger than they are in early spring or in late autumn even if they are smaller than they are in high summer and early autumn.

One note for anglers looking to fish Yellowstone Park at this time: while there’s plenty of fishing to be had, only a couple of fisheries that are ready in late spring offer reliable fishing for good sized (12-18” or better) fish. Most of the lakes and streams instead offer consistent fishing for trout averaging under about 13 inches. If you want big ones and want to fish the park rather than outside it, stick to Yellowstone Lake. Fly fishing Montana in late spring generally offers larger fish than fly fishing Yellowstone Park at this time.