Tghe south fork of the Snake river on a rainy day and bald eagle flying overhead.

Fishing for Trout in the Rain

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Fishing the rain for trout in Northern IdahoWhile I am out on the river guiding all summer and a massive storm, or even a light rain; I get asked almost every time: will we catch fish in this heavy rain? There are a lot of factors that seem to play a role in how good fishing will be during and after a heavy rain. I will get into those in just a moment. Right now I want to bring up a major tip for fishing in thunder storms—JUST DON’T DO IT! Holding a 9-10′ long conductor in the air and swinging it around during an electrical storm is just not smart.

There is no way of telling whether or not the rain will have a positive or negative effect on your fishing trip. I have seen fishing get very good during a rain—I have also seen it shut down entirely, with no more action at all after it began. Below I will explain my observations and experiences in various types of rainy weather.

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Factors that Seem to Play a Role in Fishing During the Rain

  1. Cold Rain/Hail: If the rain is significantly colder than the water temp, it could trigger some serious feeding activity, or it could shut them down completely. I have noticed that in the early fall and summer when water temps in the river are colder than the trout would like, a cold rain can cause a mega feeding frenzy. It is very common for these drastic and sudden water temp. changes to trigger a huge hatch as well during, or just after the storm. Even large amounts of hail can often trigger fish to go haywire shortly after it has finished falling.
  2. Very Heavy Rain: If you can see your dry fly out there (and see the hits) and can keep it floating during major rain, you could catch a lot of fish. If it has been raining for a while and you aren’t seeing any activity on the surface, you should put on a nymph rig. The heavy rains will have washed a lot of food for the trout off the banks and trees into the river—and it won’t be floating on the surface. You could always try the San Juan worm, because worms are always out and about during the rain. If the rain water has changed the color of the river, you might also try to throw some brighter colored flies. Read more about fishing in dirty/stained water here.
  3. Light Rain: In my experiences, a light mild rain will not usually have much effect on fishing at all.
Tghe south fork of the Snake river on a rainy day and bald eagle flying overhead.
This day it rained on and off all day long, however there was a massive blue winged olive hatch making fishing spectacular even though it was wet and cold.

Rainy Day Tactics

Streamers

Streamers will often become very effective during the rain, but it really depends on the day. If the hatch shuts down and fish stop hitting the surface, streamer fishing might be your best choice. My personal starter flies in a dark rain storm will usually be black, but olive colored patterns have also been good to me in dark weather.

Nymphing

Running a double or triple nymph rig can be very good choice in the rain. You might have to completely change the bugs that the fish were hitting prior to the weather coming in, but something will probably work—you just have to figure out what it is.

Summary

Every rain will effect the fish differently. It will also effect your moral in a hurry if it gets chilly, but leaving the river during the rain does not have to be your only option. My very best days of fishing have taken place during and after heavy storms rolled through. Take cover if you must during the extreme weather, but once it’s done—get back out there and try some more; it could blow your mind!