Ohio Lake Water Temperatures
Typical surface water temperatures for 7 Ohio lakes. Tappan Lake runs warmest (~79°F in summer); the statewide summer average is about 77°F. Values are typical by month, not live readings.
Ohio lakes by typical summer water temperature (warmest first)
| Lake | County | Summer avg | Warmest | Coldest |
|---|---|---|---|---|
| Tappan Lake | Harrison | 79°F | 80°F (Jul) | 63°F (Oct) |
| Seneca Lake | Noble | 79°F | 82°F (Jul) | 71°F (May) |
| Buck Creek Lake | Clark | 79°F | 81°F (Jul) | 69°F (May) |
| Sites Lake | Richland | 79°F | 81°F (Jul) | 66°F (Oct) |
| Charles Mill Reservoir | Ashland | 78°F | 79°F (Aug) | 65°F (Oct) |
| Pleasant Hill Reservoir | Richland | 76°F | 78°F (Jul) | 62°F (Oct) |
| Caesar Creek Lake | Warren | 66°F | 71°F (Sep) | 50°F (Apr) |
More Ohio lake data
Frequently asked questions
Which Ohio lake has the warmest water?
Of the 7 Ohio lakes with a temperature record, Tappan Lake in Harrison County runs warmest, averaging about 79°F at the surface in summer. Colder lakes like Caesar Creek Lake sit closer to 66°F.
What is a typical summer water temperature in Ohio?
Across the Ohio lakes we track, typical summer surface temperature averages about 77°F, though it varies widely by lake depth, elevation, and region. Shallow lowland lakes warm faster and further than deep or high-elevation ones.
Where does this Ohio water temperature data come from?
Each temperature is a typical (climatological) value computed from real surface-water field readings collected by state and federal agencies and published through the EPA Water Quality Portal. They describe what is typical for each month, not the temperature right now.
About this data
Water temperatures are a climatology — the typical value for each month, averaged from real surface-water field readings published through the EPA Water Quality Portal. They tell you what to expect, not the temperature right now.