Trout are cold-blooded, so the water temperature sets their metabolism, where they hold, and whether they feed at all. Read the temperature first and the rest of your plan follows. This is the master variable, and it is the heart of what FishCast scores.
Three windows to know, with a cheap stream thermometer in your pocket:
- 50-65F is prime. Fish are active and willing, feeding through the day. Most hatches key on bands inside this range, so bugs come off and trout look up - good news for fly, spin, and bait alike. Fish where you would expect them, like seams, runs, and holding-water, and a normal presentation works.
- Below 45F they slow down. Their metabolism drops, so they go deep and feed in short midday windows. Slow everything down and put it right on their nose, whether that is a drifted nymph, a slow-rolled spinner, or bait on the bottom. In winter, fish the warm afternoon edge once the sun has nudged the water up a degree or two.
- Above 68F they get stressed. Warm water holds less oxygen. Over about 70F, stop fishing entirely - a hooked fish often will not survive release. In summer, chase the cool, oxygenated riffles and fish the early morning before the water peaks.
Where you fish changes how stable that number is. A tailwater runs cold and steady year-round because it pulls from the bottom of a dam. A small freestone swings with the air, warming fast on a sunny afternoon and cooling overnight.
One reading tells you the window, the spot, and whether to fish at all.