Watts Bar Lake water temperature right now
As of , Watts Bar Lake water temperature is 71.1°F (71°F rounded), measured by a submerged Ecowitt WN34BL probe at Tennessee River Mile 559.5 in Roane County, Tennessee. Trend over the last 24 hours: -2.2°F (cooling).
What the value means
Surface water temperature on a TVA reservoir like Watts Bar swings substantially with season, depth, and recent generation. The probe sits in mid-column off a dock at TRM 559.5; it tracks open-water temperature in the main channel within roughly half a degree on calm days. After a heavy generation cycle or wind event, vertical mixing can push the reading 2–4°F warmer or cooler than typical embayment water within a few hours.
For fishing, the seasonal water-temp curve drives almost everything. The fishing page ties live water temp to per-species patterns: largemouth, smallmouth, crappie, striped bass, catfish, bluegill, and spotted bass. Each species page lists the water-temp ranges where they're active and the seasonal pattern by month.
For swimming, the threshold most people care about is whether the lake is comfortable enough to spend more than a minute in. The swim guide has the temperature ranges plus per-park guidance for the public swim beaches at Rhea Springs, Hornsby Hollow, and Roane County Park. The today page surfaces the current swimming verdict directly.
Frequently asked
What is the current water temperature of Watts Bar Lake?
As of just now, the live reading from the submerged probe is —°F. The full dashboard with hourly trend is on watts.bar.
Where is the water temperature measured?
From a private dock at Tennessee River Mile 559.5 in Roane County, Tennessee. The sensor is an Ecowitt WN34BL submerged temperature probe, mid-column off the dock. The dock is on the main channel reach between Rockwood and Spring City.
How often does the water temperature update?
Roughly once per minute. The probe reports to a Home Assistant instance at the dock; a Cloudflare Worker publishes the latest reading to data.watts.bar/weather.json every minute on the cron tick.
Is the lake warm enough to swim?
Most people are comfortable swimming above about 70°F, very comfortable above 75°F. The full breakdown by temperature range, plus per-park swim guidance, is on the swim page.
When does Watts Bar Lake usually warm up enough to swim?
Mid-May is the typical inflection point. The lake tends to cross 65°F in early to mid May and 70°F by Memorial Day in a normal year. A cool spring pushes that back a week or two, especially in the upper river above Rockwood, which warms last because the inflow is colder.
How does dam generation affect water temperature?
TVA generation pulls cooler water from depth and discharges it downstream. Within Watts Bar Reservoir itself, generation usually doesn't change the surface temperature much. Below the dam in the Watts Bar tailwater, water runs consistently several degrees cooler than the reservoir, which is why trout fishing works there year-round.
What does the 24-hour change number mean?
It compares the current reading to the reading from exactly 24 hours ago. Positive means the lake is warming, negative means cooling. Day-over-day swings are usually small (a degree or less) unless a cold front, hard rain, or sustained generation pulls cold water from depth.
Why does the temperature here differ from other sources I've seen?
Most public lake-temperature sources are estimates, satellite-derived, or come from sensors at different depths or elevations. This reading is from a dedicated probe submerged off a dock at TRM 559.5, mid-column. It tracks main-channel surface conditions within roughly half a degree on calm days. It can read warmer or cooler than embayment or back-creek water by a few degrees after wind or rain events.
Want everything else live? View the full lake dashboard at watts.bar: current air temperature, wind, dam generation, lake elevation, dock cam, and 10-day forecast. Or skip to the right-now summary at /today/.