Fly Fishing Education and Gear | Why do I Need a Stream Thermometer?

Why Is A Stream Thermometer Important For Fly Fishermen?

Most serious fly fishermen have a stream thermometer stashed somewhere in their vest, chest pack, or boat bag. But it seems like they seldom dig it out and actually put it to work. What many anglers (and even guides) fail to realize is that changes in water temperature dictate so much more than just the comfort of our hands and feet.

Trout and insects alike respond immediately to sudden temperature changes and, as fly fishermen, we need to do the same. Proper use of a reliable thermometer can help anglers anticipate hatches, find fish, and protect our resource. Almost every company that manufactures fly fishing tools and  accessories has some kind of thermometer in their lineup. But, my favorite, and the one I use is the Fishpond Swift Current Thermometer. It has a few features that I like, but probably my favorite thing about it is its simple design.

Easy to Use

Sometimes simple is better, and I have found that such is the case with many of my angling accessories. Too many features and add-ons can make a good tool cumbersome and inefficient. For example, a lot of fly fishermen buy digital thermometers only to find that they cannot read the screen while wearing polarized sunglasses. I would rather look at a red line quickly than risk scratching or losing my sunglasses by taking them off to read water temperature.


The Fishpond Swift Current accurately displays temperatures from 20 to 120 degrees Fahrenheit without needing to be recalibrated throughout the life of the thermometer. I test it against other thermometers every once in a while, and it still reads the correct temperature after several seasons of use. Reliable gear is a must for serious fly fishermen.


The high strength aluminum casing surrounding the Fishpond Swift Current thermometer has stood up to more abuse by me than any thermometer ever should. Mine has spent countless hours either dangling out of the side of my boat or bouncing along rocky streambeds, and has no signs of breaking down. Durability is so important for small tools like this. The Swift Current is a great example of a tool that will last. It even comes in bright colors that make it easy to keep track of.

A Few Key Temperatures to Keep in Mind

Water temperature fluctuates so much more here on Colorado’s western slope than many other trout fisheries and it is critical to know not only specific temperatures, but to stay on top of warming and cooling trends. Anglers anxiously await that magical 50 degree Fahrenheit mark, for example, to signal the beginning of the salmon fly hatch on the upper Colorado River or caddis on the Eagle River near the Vail Valley Anglers fly shop. Later on in the heat of the summer, conscientious fly fishermen avoid fishing during times of the day when the water is warmer than 68 degrees Fahrenheit so as not to overstress and kill already weakened trout. Sudden increases or decreases in water temperature can turn fish off completely, while more gradual temperature changes can encourage feeding.

Want to catch more fish? Buy a durable, accurate thermometer like the Fishpond Swift Current, and pay more attention to water temperature. For this and other important gear and gadget choices consult the fly fishing experts at Vail Valley Anglers in Edwards. Colorado.

Andy “Otter” Smith, Guide and Content Writer