William H Harsha Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in William H Harsha Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in William H Harsha Lake today is 26.4°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 79°F (26°C) to 82°F (28°C). This is very warm water, allowing for extended stays without any discomfort. Swimming in these conditions will be particularly enjoyable, making it the ideal temperature range for those who want to relax in the sea. Additionally, water in this temperature range is suitable for children and elderly people, as it is comfortable for prolonged stays. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| JUL 14 | 26.7°C | 23.6°C | |
| JUL 15 | 29.1°C | 23.6°C | |
| JUL 16 | 27.2°C | 23.6°C | |
| JUL 17 | 26.8°C | 23.6°C | |
| JUL 18 | 26.2°C | 23.6°C | |
| JUL 19 | 26.4°C | 23.6°C | |
| JUL 20 | 26.3°C | 23.6°C | |
| JUL 21 | 26.2°C | 23.6°C | |
| JUL 22 | 23.6°C | 26.3°C | |
| JUL 23 | 23.6°C | 26.1°C | |
| JUL 24 | 23.6°C | 26.0°C | |
| JUL 25 | 23.6°C | 25.8°C | |
| JUL 26 | 23.6°C | 25.7°C | |
| JUL 27 | 23.6°C | 25.6°C | |
| JUL 28 | 23.6°C | 25.4°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 3°C | 9°C | 14°C |
| February | 2°C | 9°C | 16°C |
| March | 2°C | 11°C | 19°C |
| April | 8°C | 14°C | 20°C |
| May | 14°C | 18°C | 22°C |
| June | 19°C | 22°C | 25°C |
| July | 18°C | 24°C | 30°C |
| August | 22°C | 24°C | 27°C |
| September | 21°C | 24°C | 26°C |
| October | 18°C | 21°C | 24°C |
| November | 8°C | 14°C | 19°C |
| December | 4°C | 9°C | 13°C |
William H Harsha Lake: Water Temperature by Location
William H Harsha Lake: Weather Forecast
July 22
July 23
July 24
July 25
July 26
Location & Local Information
William H. Harsha Lake in southwestern Ohio experiences wide seasonal variation in surface water temperature. In winter the lake hovers near freezing, roughly 33–40°F (1–4°C). Spring brings a gradual rise, typically 40–60°F (4–15°C) depending on air temperatures and runoff. By summer the surface commonly warms to about 68–80°F (20–27°C) at the peak of the season, though shallow coves can be a few degrees warmer on hot days. During autumn the water cools back into the 50–65°F (10–18°C) range as air temperatures decline. These are general ranges and actual readings vary day to day with weather, depth, and time of day.
Swimming at William H. Harsha Lake is generally allowed but is subject to management rules and seasonal openings of designated areas; many reservoirs permit swimming only in marked spots and do not provide lifeguards. Recreational use is balanced with boating, variable depths, sudden temperature changes, and occasional water-quality issues such as algal blooms, so officials may post advisories or close areas for safety. Visitors should check current advisories, use caution around boat traffic, and remember that colder or near-surface layers can produce strong thermal shock even on warm days, making cautious entry and awareness of conditions important.