One of the most important items in the fishing vest is your thermometer. Sometimes temps are the most crucial factor when choosing a place to fish. As a general rule, 61 or 62 is about prime for rainbows; add one or two degrees more for Browns. Whenever temps move towards the prime, fishing tends to improve.
Right now on the
Madison the water temps are starting in the morning around 48 degrees—cold on the toes if one is wading wet. By 3:00 or 4:00 in the afternoon temps peak out at about 60. What does it all mean? Relax, sleep in, have a nice breakfast—fish are not out of bed yet. This has been working out well for me lately. Most guides are meeting their clients at 7:30 or 8:00 in the morning. I have been getting going around 10:30 or 11:00. By the time I get to the put in, everyone else is long gone, the temps are on the way and the fish are waking up.
Earlier this year when air temps were topping out in the low-to-middle 90s, the situation was reversed. Water temps were topping out in the low seventies and fishing was dead by 2:00 in the afternoon. I was picking up clients at 4:30am in the dark, fishing the first half hour in the dead dark with absolutely no one around. Temps hovered right around 60 degrees by 6:00am. Killer fishing all alone and home playing video games in a dark cool basement by 1:30.
Temps become especially critical during winter and spring. Some people are crazy enough to go fly fishing in the winter. This is when a couple of degrees can make a big difference in my experience. The lower threshold is 40 degrees, with the upper being about 70. Winter water temps often hover down around 36 or 37. When they do, fishing sucks. If you get a warm day and those temps bump up above to the 40-degree threshold, it becomes show time. The difference between 38 and 40 is huge.
Our section of the Madison comes first out of Hebgen reservoir, the out of quake lake. In the winter months the warmest water is coming out of the lakes, usually around 45 to 48 and getting colder as it moves down the valley. When I'm looking for a good place to fish with appropriate temps I drive up the river, stopping at various access points and checking temps as I go. I keep going until I find that magic number of 40 degrees. Once I find that spot, it’s time to fish.
Temperature can make a big difference in how your day goes.
Read More Strategies for Winter Fly Fishing in Montana