Estimated surface temperature for Lake Joy in King County, Washington, updated with live National Weather Service air temperatures and a seasonal model tuned to this lake's latitude and depth. Use it to plan fishing, swimming, and boating — then verify on the water.
Water temperature
Modeled surface-temperature estimate built from seasonal climate, lake depth, and live National Weather Service air temperatures near this lake.
Seasonal estimate. Checking current National Weather Service air temperatures…
Comfortable summer pattern. Bass and panfish are active; early and late hours beat the midday heat.
| Month | Typical surface temp | Conditions |
|---|---|---|
| January | ~32°F | Iced over or near freezing |
| February | ~32°F | Iced over or near freezing |
| March | ~32°F | Iced over or near freezing |
| April | ~34°F | Iced over or near freezing |
| May | ~49°F | Cold |
| June | ~62°F | Cool |
| July | ~71°F | Warm |
| August | ~73°F | Warm |
| September | ~67°F | Warm |
| October | ~55°F | Cold |
| November | ~41°F | Frigid |
| December | ~32°F | Iced over or near freezing |
Estimates are modeled, not measured. Actual temperatures vary with depth, wind mixing, and recent weather — verify conditions before swimming, boating, or heading onto ice.
Water temperature FAQ
LakeList currently estimates the surface temperature of Lake Joy at about 72°F (warm). This is a modeled estimate from seasonal climate, lake depth, and National Weather Service air temperatures — actual readings vary by day, depth, and location on the lake.
Surface temperatures at Lake Joy typically peak in August, reaching around 73°F in an average year. Shallow bays warm faster than the main basin, so mid-summer readings can run a few degrees higher near shore.
Modeled surface temperatures at Lake Joy drop to freezing from about December through April in a typical year. Actual ice-up and ice-out dates vary season to season, and ice thickness is never guaranteed — always check current local ice reports before heading out.
LakeList models the seasonal surface-temperature cycle from the lake's latitude and depth, then adjusts it with current National Weather Service air temperatures near the lake. Deeper lakes warm and cool more slowly than shallow ones, so the model lags and dampens the air-temperature cycle accordingly. Treat it as a planning estimate, not a measured reading.