Ohio Lake Water Temperatures
Typical surface water temperatures for 6 Ohio lakes — about 74°F in September. Seneca Lake runs warmest (~79°F in summer); the statewide summer average is about 78°F. Values are typical by month, not live readings.
Ohio lakes by typical summer water temperature (warmest first)
| Lake | County | Typical in September | Summer avg | Warmest | Coldest |
|---|---|---|---|---|---|
| Seneca Lake | Noble | 76°F | 79°F | 82°F (Jul) | 71°F (May) |
| Buck Creek Lake | Clark | 75°F | 79°F | 81°F (Jul) | 69°F (May) |
| Sites Lake | Richland | 76°F | 79°F | 81°F (Jul) | 66°F (Oct) |
| Charles Mill Reservoir | Ashland | 71°F | 78°F | 79°F (Aug) | 65°F (Oct) |
| Tappan Lake | Harrison | 72°F | 78°F | 78°F (Jun) | 71°F (May) |
| Pleasant Hill Reservoir | Richland | 75°F | 76°F | 78°F (Jul) | 62°F (Oct) |
More Ohio lake data
Frequently asked questions
Which Ohio lake has the warmest water?
Of the 6 Ohio lakes with a temperature record, Seneca Lake in Noble County runs warmest, averaging about 79°F at the surface in summer. Colder lakes like Pleasant Hill Reservoir sit closer to 76°F.
What is a typical September water temperature in Ohio?
Across the Ohio lakes we track, typical September surface temperature averages about 74°F. That is a climatological value from EPA field readings, not the temperature right now. Summer averages about 78°F.
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.