Water temperature & Seasons

Have you ever taken a plunge into freezing cold water?

Perhaps you’ve even fly fished before and accidentally lost your footing. Taking that unexpected plunge certainly shocked your 98.6 degree fahrenheit warm blooded system.

To contrast that with fish, they thrive in (relatively) colder water.


It all has to do with Oxygen (Yes, even fish need oxygen to survive). In water, the oxygen is dissolved. As water temperatures rise, the amount of dissolved oxygen decreases↓. Likewise, lower water temperatures increase↑the amount of dissolved oxygen. High water temperatures can even be lethal!

So what temperature are we talking?

The optimal temperature for a trout is 45-58 degrees fahrenheit. This fluctuates slightly depending on the species that you’re after.


"What good is the warmth of Summer, without the cold of Winter to give it sweetness." - John Steinbeck

The winter months are usually the least fruitful in fly fishing. With the freezing water temperatures, a trout becomes lethargic and takes the path of least resistance to conserve its energy. Nature still takes care of these fish by providing midge hatches throughout the year, even the cold winter months. A trout will spend its time in slower currents and tends to only feed during these midge hatches, which are difficult to detect.

The hatches typically happen during the day, completely opposite of the meal times and bug activity typical of the other months of the year. There are often tailwaters (rivers that come out of reservoirs) where the temperature is more regulated, thus creating close to ideal water temperatures, even during the cold months of January. If you’re going to venture out to fly fish in the winter, target these waters.

Although the weather can bring numb fingers and toes, there are some benefits to fly fishing in the Winter.

First, you get to sleep in! No more dawn patrol early morning drives to the river. The best fishing and possibility of hatches is during the warmest part of the day (usually around noon). Watch for small midges on the water’s edge or the occasional Blue Wing Olive to float by. However, the majority of bug activity will be below the surface. Time to master your nymphing and streamer abilities.

Second, only the die hards will brave the cold weather. This means less crowds and more water to yourself. Instead of venturing off grid in search of secluded tributaries, it may be possible to visit water often crowded during the Summer months. Less pressure can make the fishing better as well.

Overall, winter fishing if done right can be very productive and enjoyable. Prepare well and dress warm.


Spring and Fall are the most productive fly fishing seasons. There are many factors that play into this; however, most of it can be broken down into two:

1. Bug Activity

2. Favorable Water Temperatures (Recall the water temperature section)

In Spring, the snow will melt and a runoff will take its course for a few weeks. Once the torrential water passes, crystal clear waters emerge, and the fish begin a feeding frenzy.

In the fall, after the long hot summer months, the cooler Fall air temperatures slowly cool the water down to optimal fish temperatures.

The fish know Winter is coming soon, and they’ll start to gouge themselves with all the available food, fattening up for the difficult months ahead.


Remember your 9th Grade Science Class?

Ya us neither! 😂 You likely talked about how water temperatures are way more resistant than air temperature. In the summer months, you can use this knowledge to your advantage.

During the hot sunny days of summer, the water temperature slowly rises. Your best time to fish is in the morning because the water temperature has cooled off during the night, and the fish will be more active as they feed on morning bug hatches.

As the day progresses to the afternoon, the fish will start to move from their feeding lanes to deep pocket water and under banks. You’ll likely need to change tactics by throwing a large terrestrial near the banks to get to where the fish are chilling (literally!).

The evening will be more fruitful than the afternoon with more bug hatches; however, it will likely be less rewarding than the morning hours. Even with the evening's dramatic air temperature drop, the water will still require several hours before it cools off to the fish’s liking.