UTERFish bite best when the water is in the middle of their preferred temperature range: roughly the 40s for lake trout, the upper 40s to 50s for salmon and steelhead, the 50s and 60s for walleye and striped bass, the 60s to low 80s for largemouth bass, redfish and speckled trout, and the mid-70s and up for snook, tarpon and other tropical fish. Fish are cold-blooded, so water temperature sets how fast they digest and how hard they hunt. That makes it one of the best single predictors of what will bite in any water on any day.
Below is a species-by-species temperature chart, the spawn triggers state agencies publish, and an honest look at how Fish Scouter's forecast uses water temperature to rank the fish where you're standing.
Why water temperature matters so much
A fish's body runs at the temperature of the water around it. Inside its comfort band it feeds, grows and moves freely; toward the cold edge it slows down and needs less food; past the warm edge oxygen gets scarce and it stops feeding to survive. That's why the same flat can be full of feeding redfish one week and empty the next after a front drops it 10 degrees, and why spawning runs (walleye up the Maumee, salmon up the Salmon River, stripers up the Chesapeake rivers) start on temperature more than on the calendar.
Temperature also tells you where in a water to look. In summer, cold-water fish drop below the thermocline. NYSDEC describes it on Lake Ontario as a narrow band, often only 5 to 15 feet thick, where the temperature falls fast. In winter, warm-water fish look for the warmest water available: deep creek holes, spring runs, power-plant discharges, sun-warmed mud flats in the afternoon.
Water temperature chart by species
These are the ranges Fish Scouter's forecast uses. "Ideal" is where we score a fish highest; "feeding range" is where it will still eat. They're a rule of thumb, drawn from agency guidance and guides' experience, and individual waters vary.
| Species | Ideal (°F) | Feeding range (°F) |
|---|---|---|
| Cold water | ||
| Lake trout | 44–54 | 34–60 |
| Brook trout | 46–60 | 34–66 |
| Steelhead | 44–56 | 38–62 |
| Chinook salmon | 50–56 | 44–60 |
| Coho salmon | 50–58 | 46–62 |
| Rainbow trout | 48–62 | 36–70 |
| Brown trout | 50–64 | 36–72 |
| Atlantic cod | 40–52 | 36–58 |
| Cool water | ||
| Northern pike | 50–68 | 33–76 |
| Striped bass | 50–68 | 42–80 |
| Tautog | 50–64 | 44–72 |
| Walleye | 55–70 | 34–78 |
| Yellow perch | 55–72 | 34–80 |
| Muskellunge | 55–75 | 38–82 |
| Smallmouth bass | 60–74 | 45–82 |
| Bluefish | 62–74 | 58–80 |
| Summer flounder (fluke) | 62–74 | 56–80 |
| Crappie | 56–72 | 38–86 |
| Warm water | ||
| Largemouth bass | 62–80 | 45–92 |
| Sheepshead | 54–66 | 48–74 |
| Black drum | 54–70 | 48–78 |
| Speckled trout | 62–78 | 54–86 |
| Southern flounder | 60–75 | 54–82 |
| Redfish | 65–82 | 58–90 |
| Channel catfish | 70–84 | 45–92 |
| King mackerel | 68–76 | 66–82 |
| Tropical and blue water | ||
| Snook | 74–86 | 68–90 |
| Tarpon | 78–86 | 74–90 |
| Mahi-mahi | 76–84 | 72–88 |
| Yellowfin tuna | 74–80 | 72–84 |
Spawn triggers state agencies publish
Spawning is where temperature is most precise, and where agencies have measured it:
- Walleye: Wisconsin DNR says spawning usually peaks in 42 to 50°F water, generally mid-April to early May in that state. That matches the Lake Erie tributaries, where the Maumee run starts once the river passes the low 40s (see our Lake Erie walleye guide).
- Largemouth bass: Wisconsin DNR says nest-site selection begins when the water reaches 60°F and eggs are laid at 62 to 65°F. Farther south the spawn is earlier in the year but on the same temperatures.
- Trout and salmon in the Great Lakes: NYSDEC's Lake Ontario table gives preferred ranges of 52 to 58°F for chinook and coho (optimum 53), 55 to 65°F for rainbow trout and steelhead, 54 to 63°F for brown trout and 42 to 52°F for lake trout (optimum 48). Note these are open-lake preferences; river-run fish bite in colder water, which is why our steelhead range sits lower. Our Great Lakes runs guide has the timing.
- Snook: snook are cold-sensitive. An FWC spokesperson has described the mid-50s as about the lowest they can tolerate, with cold stress starting around there or a little warmer. That's why a Florida cold snap sends snook to deep creeks and canals, and why the forecast stops ranking them when the water falls below the upper 60s.
How Fish Scouter uses water temperature
Fish Scouter ranks every species in your water for the hour you're fishing, and water temperature is one of the biggest inputs. Here is exactly how it works, because we think you should be able to see why a fish is ranked where it is.
Where the reading comes from
- Coasts: the nearest NOAA tide station that is actually reporting water temperature.
- Rivers: the nearest USGS gauge with a live temperature reading, along with its flow.
- Great Lakes: NOAA GLERL's daily satellite surface temperature.
How it's scored
Each species has an ideal band and a wider feeding range (the chart above). Water in the ideal band adds the most to the score; water in the feeding range adds a little; water outside it takes points away, more the further out it is. The app says which, in plain words: "62°F is ideal water," "54°F is cold for them."
Temperature isn't the whole score. The forecast also weighs:
- The season: each water's calendar says whether a fish is arriving, at its peak, spawning, leaving or absent this month. A redfish in perfect water in a month it's not there still won't rank.
- Moving water: how hard the tide is flowing (on the coast) or whether the river is rising, steady or dropping after a rise (in fresh water).
- Light: dawn and dusk, weighted by how much each species feeds in low light.
- Pressure and wind: a falling barometer before a front helps; a hard rise behind it hurts; 20 knots of wind hurts.
- Catches nearby: recent catch reports in the area nudge a species up.
The score is a heuristic, a guide's rule of thumb written down and applied to live data every hour. It's not a promise. It is a fast, honest answer to the question "what should I fish for here, now?"
Using temperature on the water
- Look for the edge: a 2 to 3 degree difference (a creek mouth, a spring, a current seam, a sunny shoreline in winter) is often where the fish are.
- Follow the trend: rising water in spring and falling water in fall both trigger feeding as fish move through their ideal band. See our fall fishing guide by region for what that means this month.
- Surface isn't depth: in summer on deep lakes, the surface reading tells you where the fish aren't. Find the thermocline on your graph.
- Time of day changes it: a shallow flat can swing 5 to 10 degrees between dawn and late afternoon. In winter the warmest afternoon hours are often the bite; in summer, the coolest first light is.
- Rain and runoff: a cold rain can chill a river or a marsh fast and shut the bite down, while a warm rain in early spring can start a run overnight.
- Handle warm-water fish gently: stripers and trout released in hot water die more often. Keep fights short and fish in the water.
Let the water tell you what's biting
We think Fish Scouter is the best way to know what's biting, because it does this temperature-and-season math for you at every spot and shows its working. Open the app on any US coast, the Great Lakes or a river, and it ranks the fish for the water you're on, with the reasons in plain words and the next seven days scored. Try Fish Scouter free.