Important Websites for Planning Your 2019 Yellowstone Fly Fishing
It's the time of year when I receive a lot of questions about the best time to plan a fly fishing trip for Southwest Montana and Yellowstone National Park. There are no easy answers to this question. Forecasting weather trends and runoff isn't a perfect science, but the websites I'm including in this blog can help.
The greatest factors for determining when to schedule your trip are snowpack and where you want to fish: lakes, spring creeks, dam-controlled rivers and streams, or free-stone rivers and streams. Yellowstone National Park doesn't open to fishing until late May, the Saturday of Memorial Day weekend (some waterways open later). Rivers such as the Firehole and some lakes and ponds (like Trout Lake) are usually fishable when the Park opens, but most others typically don't offer good, reliable fishing conditions until sometime in June or even early July. All of this is dependent upon snowpack and run-off rate due to air temperature.
The Yellowstone River in Montana will generally have good to great fishing after ice-out (usually sometime in Late February or March) until full-blown runoff occurs, most often in early May around Mother's Day. Low elevation run-off will begin before the mountain snowmelt, and this may dirty the river for a few days or a week, but fishable conditions usually return before the big upper elevation melt begins. Pre-runoff fishing usually ends with the Mother's Day Caddis hatch (Brachycentrus sp.). Fishing during this hatch can be terrific, but you have to be prepared for it to start. Usually, once the caddis have been hatching for about a week, warm air temps instigate higher elevation runoff that makes the river high, dirty and unfishable, and these conditions persist until sometime from late June to mid July.
So how does this information help you plan your trip? First, you need to look at the Snow-Precipitation chart. This will give you an idea as to how much snow needs to melt for conditions to return to fishable levels post-runoff. But this won't give you the whole picture. It would be easy if you could say above average snow, with a high water content, makes runoff last longer into the year. But you can't. Runoff can be accelerated if the weather turns unusually warm or delayed if it stays cool.
I often tell people that the second week of July through the summer and fall is the best time to fish. But if you religiously adhere to these dates, some years you can miss some great opportunities for hungry trout in early July or even late June. If possible, the best approach is to remain flexible when booking your trip--wait to see how runoff is proceeding before you plan to come to Montana. But not everyone can do that. Vacation times often need to be planned well in advance. If you're in that situation, then the old adage that the best time to fish is whenever you can certainly comes into play. No matter the river conditions, there's almost always somewhere to fish here. And even if conditions make your trip a little less than perfect, you're still in Montana. Or still in Yellowstone National Park. Things could be much worse.
To find the current snowfall and water content levels, verses historical norms, look here:
University of Wyoming's Snow-Precipitation Update
To see current verses historical river and stream flow data, check here:
Montana USGS Guages
Wyoming USGS Guages
For current weather conditions along the Yellowstone River in Montana's Paradise Valley, look here:
NOAA Weather for Emigrant, MT