Lake Water Temperatures
Typical surface water temperature for 416 lakes across 1 states, month by month — from real EPA field readings. See which lakes are warmest, when they peak, and whether the water is warm enough to swim.
Warmest lakes right now (typical for July)
| Lake | State | Typical in July | Summer peak |
|---|---|---|---|
| Otter Lake | Wisconsin | 89°F | 75°F |
| Taylor Lake | Wisconsin | 89°F | 78°F |
| Booth Lake | Wisconsin | 84°F | 81°F |
| Crystal Lake | Wisconsin | 83°F | 78°F |
| Eagle Spring Lake | Wisconsin | 83°F | 80°F |
| Wolf Lake | Wisconsin | 82°F | 79°F |
| Moon Bay Lake | Wisconsin | 82°F | 77°F |
| Lake Koshkonong | Wisconsin | 82°F | 77°F |
| Horseshoe Lake | Wisconsin | 82°F | 80°F |
| Fawn Lake | Wisconsin | 82°F | 79°F |
| North White Ash Lake | Wisconsin | 82°F | 77°F |
| Boundary Lake | Wisconsin | 82°F | 79°F |
| Spirit River Flowage Lake | Wisconsin | 82°F | 75°F |
| Lake Ripley | Wisconsin | 82°F | 77°F |
| Little Elkhart Lake | Wisconsin | 82°F | 78°F |
Water temperatures by state
Most-monitored lakes
The lakes with the deepest temperature records — the ones people most often ask about.
More lake data
Frequently asked questions
How do you know a lake's water temperature?
We compute a typical (climatological) temperature for each month from real surface-water field readings collected by state and federal agencies and published through the EPA Water Quality Portal. It tells you what is typical for a given month at that lake — not the temperature at this exact moment.
Why not show the live water temperature?
Very few lakes have a real-time temperature gauge — only a small number of large lakes carry USGS sensors. A monthly climatology is the honest, comparable answer for every lake: it is based on actual readings and covers thousands of lakes that have no live sensor. Where a lake does have a live gauge, we show that reading on its report card.
What water temperature is comfortable for swimming?
Most people find 70–80°F comfortable for swimming without a wetsuit. Below 70°F feels brisk; below 60°F is cold enough to warrant a wetsuit; and below 50°F carries a real cold-water-shock risk. Warm water (80°F+) is very comfortable but can also favor blue-green algae in nutrient-rich lakes, so check for advisories.
About this data
Water temperatures are a climatology — the typical value for each month, averaged from real surface-water field readings collected by state and federal agencies and published through the EPA Water Quality Portal. They describe what to expect, not the temperature right now.