5 Weather and Water Conditions that Affect Your Fly Fishing

A couple weeks ago, I fished Montana’s Madison River three days in a row. The first day was stellar. The second day was not. The third day was a combination of fantastic and frustrating. All of this was due to the weather and water conditions. Such conditions force fly fishers to make adjustments.

Here are five weather-and-water conditions that affect fly fishing:

1. Water Level and Color

My first day on the Madison consisted of only two-and-a-half hours in the afternoon.

I spent the prime fly fishing hours on a Delta flight to Bozeman. Yet I still caught eight healthy rainbows (and lost several more). The next day, after some good rainbow fishing at dawn on the Missouri River near Helena, I drove back to the same spot I fished on the Madison the previous day. I arrived during a prime time window.

But I noticed that the water level was slightly higher and that the color was a bit murkier. As I feared, the fishing was slow. I caught nothing the first two hours even though I tried different patterns and presentations. The adjustments eventually yielded a couple small rainbows. But nothing like the previous day.

Sometimes, no adjustment with my rig makes a difference on days with higher water levels and more color. Sometimes, though, switching to a San Juan Worm or throwing a big streamer gives me a better chance.

2. Sky

If you’re new to fly fishing, you might be surprised to know that the sky has as much effect on fly fishing as the water conditions.

An old John Denver song says, “Sunshine on the water looks so lovely.” Yes, but not to a fly fisher. A cloudy, gloomy day will often trigger insect hatches, which in turn give trout something to feed on. So whenever I see grey skies, I expect to have some decent dry fly fishing. I look for Blue-Winged Olives or whatever else might be hatching at that time of year on that particular stretch of river.

When the sun shines bright in a cloudless sky, I anticipate nymph fishing. This is exactly what I did on the Madison on day one. I saw a few mayflies on the surface, but there were no trout rising. The trout were happy to take nymphs.

However, dry fly fishing can be productive on a sunny day later in the summer when hoppers are active. A hopper pattern — or even a big attractor like a Red Humpy or a Spruce Moth — may coax a large trout from its lair.

3. Moisture

Related to the sky is the moisture in the air.

The most ideal conditions for fly fishing are not the most ideal conditions for fly fishers. Rain and snow trigger insect hatches. I had light rain throughout my third day on the Madison, and the trout were quite active.

The only adjustment to make here is to invest in a good rain jacket. If you’re new to fly fishing, never quit because it’s a rainy or snowy day! That’s a prime condition for catching trout.

4. Water Temperature

Water temperature matters, too. I used to carry a thermometer in my fly vest to check the temperature of the rivers I fished.

Honestly, it was more interesting than helpful.

But I’m keenly aware that trout are more active in colder water and more sluggish in warmer water. A guide in a fly shop in Ennis told me that the Upper Madison had incredible dry fly fishing the previous year because most of the water released from Hebgen Dam was through the pipeline at the bottom of the dam. The water at the bottom is, of course, colder than the water closer to the surface.

The stretch of the Madison I fished on day one tends to be good in the spring but one to avoid in the summer. Or, if I fish it in the summer, I fish it in the cool of the early morning — before the warmer temperatures make the trout more sluggish (and susceptible to danger if played too long).

Besides, the warmer summer days trigger the “inner tube hatch” (dozens and dozens of people and their coolers floating down the river)!

5. Wind

I can put up with moisture (which makes the fly fishing better). But nothing frustrates me more than a day where the wind whips like it does on Mount Everest. I hate wind.

My third and final day on the Madison was almost thwarted by wind. I was floating the Upper Madison with a couple of buddies, and the oarsman (a veteran rower) struggled to keep us from slamming into the bank.

Still, the fishing was fantastic — between the gusts.

Some adjustments made the difference. While I saw rising fish (due to the clouds and moisture I already mentioned), the wind made it impossible to keep a dry fly from plowing through the surface film. So I switched to nymphs. I also shortened my casts and waited to make them between gusts of wind.

Weather and water conditions are unpredictable. But that’s why it’s called “fishing”!

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