Best Water Temperature For Fishing Tributaries

Here’s a great piece of advice when fishing tributaries – keep a thermometer in your fishing vest!

Importance of Water Temperature for Tributary Fishing

Water temperature is a big factor for anglers who enjoy tributary fishing. Stream and river spawning migration is heavily affected by water temperature, food availability, and other environmental factors. Tributary water temperature governs all aspects of fish activity from their ascent up the river, to the intensity of their spawning. And therefore, temperature should influence how and where you attempt to try your hand at tributary fishing.

Understanding How Water Temperature Affects Fish

As a guide, I fish practically every day without the luxury of picking the days I want to fish. Conversely, most anglers have a choice. They can fish we they want. Understanding how fish are affected by the water temperature and its fluctuations will help you to adjust your tributary fishing schedule.

Some fishermen claim that water temperature is not that important. This may be true when the temperature of the water is stable and within the comfort range of your target species; but often, the temperature of the water fluctuates throughout the day. During late fall, early winter, and again in early spring, temperature swings can be big which can greatly impact river and stream fishing success. 

It is not unusual for temperatures to fluctuate as much as five to seven degrees throughout the day. Even a two or three degree swing in water temperature for fishing tributaries is a big deal. Often it is the temperature of the water that influences why the tributary fishing is better during one time of the day versus another.

Different Temperatures Affect Different Fish Species

man poses with large steelhead caught while tributary fishing in the early spring
Paying attention to changing water temperatures is important to tributary fishing for spring steelhead.

All species of fish have their preferred temperature range. For salmon the preferred temperature range is about 60 degrees on the high end to 50 degrees on the low end. Below 50 degrees, salmon start to become affected by cold water.

Steelhead prefer slightly cooler water, but they start to be affected by cold water if the temperature drops below 40 degrees.

For salmon and steelhead, when the water temperatures near or surpass the high side of their preferred range, the fish can just disappear, leave the river, or shut down and sit tight. 

For example, in the beginning of the salmon run in early September, water temperature can cool  slightly overnight or with changing weather conditions, and thus trigger a salmon run.

On the other hand, a change of weather can cause water temperatures rise sharply. When this happens, in extreme situations salmon in or near the estuary will often head back out into the lake. Salmon further upriver may become trapped and unable to retreat, and often succumb from warm water and the lack of oxygen.

This is one of many reasons why early salmon fishing can be unpredictable. This is not an unusual situation for the Salmon River and Lake Ontario near Pulsaki, NY in Oswego County – especially in early September.

However, don’t let warmer water stop you from fishing. With a little knowledge there is still good tributary fishing to be had.

Early Spring Steelhead Fishing

To describe how important all this can be, consider spring steelhead fishing. At about 40 degrees, steelhead start to spawn and you will find the most active fish on the gravel beds while inactive fish will still be sitting in the pools.

If we get some cold weather or a cold night and the water temperature drops a few degrees, steelhead can stop spawning and go back to a winter pattern of sitting in the pools. Sharp changes especially will affect the fish. It doesn’t have to be a cold snap to cause water temperature to drop, just a typical early spring night will do this. 

In the spring, a three to five degree temperature swing during the day is not uncommon. If this temperature swing is within the steelhead’s ideal temperature range, it would not mean much to the quality of fishing.

However, in early spring – spawning time, temperatures swings approach or exceed the lower end of steelhead’s preferred temperature range. This can have a big influence on the fish’s behavior. Paying attention to fluctuations will improve your success when fishing tributaries for steelhead.

Monitor Temperatures Frequently

When using a thermometer to assess water temperature, don’t just take a reading when you start fishing. Instead, monitor water temperature three to four times throughout the day. This will help you correlate fish activity to water temperature. This knowledge comes in handy to when you are deciding where and when to fish and will ultimately make you fishing time more productive. 

Get an Early Start

Water temperatures normally drop a few degrees overnight, so by the starting fishing day at first light I’m able to take full advantage of the cooler water temperatures and fish movement. Typically temperatures warm up by mid to late morning, thus turning the fish off. By mid to late afternoon, temperatures start to fall and fish will start to move again.   

Make Fishing Plans Around Water Temperatures

How do we use this information to turn around a potentially bad day of tributary fishing? If we know that water temperature will drop at night and shut fish down, you might consider following the fish back into the pools. 

Man wading while casting a fly rod near a small boat while tributary fishing.
Fishing with a drift boat allows you to move easily to areas with optimum water temperatures while tributary fishing.

Start your day there, but keep in mind that the fish are not that active. You need to slow down the drift and keep the flies close to the river bottom.

If the water temperatures warm back up by mid-morning, the fish will turn back on. 

When this happens, the fish will move back on the gravel and pick up where they left off spawning until water temperature, once again, gets too cold. This is one of the biggest reasons why we see the best tributary fishing in the afternoons at this time of the year. Sometimes it is best to start the fishing day mid-morning and plan to fish late into the day. I call this fishing on the fish’s schedule.   

Temperatures are an Important Tributary Fishing Factor

Water temperature is not the only governing factor that we have to consider when we go tributary fishing. However, the temperature of the water is one of the biggest factors when it comes to influencing fish behavior. Checking and understanding the effect temperature of the water has on the fish will help us turn a tough day into a great day of tributary fishing. 

Original Article By: Jay Peck

About The Author

Jay Peck is a fishing guide on the Lake Ontario tributaries. With 40+ years of fly fishing experience including 30 years as a licensed New York State guide, Jay has been applying his knowledge of the sport and local waters to help anglers in their pursuit of migratory fish, inland trout, and a variety of warm water species. Jay is also an accomplished spey caster and fly tyer. He has developed several fishing techniques and fly patterns for fishing the tributaries and inland trout streams. To learn more, check out Jay’s youtube channel, and get in touch with Jay at

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