Ontelaunee Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Ontelaunee Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Ontelaunee Lake today is 21.2°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 68°F (20°C) to 74°F (23°C). The water is warm and pleasant for swimming, and in this range, one can stay in the water for extended periods without the risk of hypothermia. This is the ideal temperature for relaxation, swimming, and water sports. Families with children, as well as outdoor enthusiasts, will enjoy swimming and time spent in the water. For most people, this is the optimal temperature for a comfortable beach experience. 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 |
|---|---|---|---|
| JUN 3 | 17.5°C | 22.5°C | |
| JUN 4 | 18.3°C | 22.5°C | |
| JUN 5 | 19.0°C | 22.5°C | |
| JUN 6 | 19.2°C | 22.5°C | |
| JUN 7 | 20.1°C | 22.5°C | |
| JUN 8 | 20.1°C | 22.5°C | |
| JUN 11 | 22.5°C | 21.3°C | |
| JUN 12 | 22.5°C | 21.3°C | |
| JUN 13 | 22.5°C | 21.4°C | |
| JUN 14 | 22.5°C | 21.5°C | |
| JUN 15 | 22.5°C | 21.5°C | |
| JUN 16 | 22.5°C | 21.6°C | |
| JUN 17 | 22.5°C | 21.7°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 | 1°C | 4°C | 7°C |
| February | 1°C | 4°C | 7°C |
| March | 1°C | 5°C | 10°C |
| April | 8°C | 14°C | 20°C |
| May | 13°C | 18°C | 22°C |
| June | 15°C | 23°C | 30°C |
| July | 19°C | 26°C | 33°C |
| August | 22°C | 27°C | 31°C |
| September | 20°C | 23°C | 25°C |
| October | 12°C | 16°C | 20°C |
| November | 5°C | 9°C | 13°C |
| December | 2°C | 5°C | 7°C |
Ontelaunee Lake: Water Temperature by Location
Ontelaunee Lake: Weather Forecast
June 9
June 10
June 11
June 12
Location & Local Information
Lake Ontelaunee, a reservoir in Berks County, Pennsylvania, experiences typical temperate-season variation in surface water temperatures. In spring (April–May) surface readings commonly range from about 45–60°F (7–16°C) as the water warms after winter turnover. Summer (June–August) brings the warmest conditions, with surface temperatures most often between 70–80°F (21–27°C) and occasionally reaching the low 80s°F (around 28–29°C) during heat spells. Fall (September–November) sees cooling waters in the neighborhood of 50–65°F (10–18°C) as air temperatures drop, and winter (December–March) temperatures typically hover near freezing, roughly 33–40°F (1–4°C), with ice possible in prolonged cold snaps. Deeper, stratified areas remain colder than surface measures year-round.
Swimming at Lake Ontelaunee is generally not permitted because the lake serves as a municipal water supply and is managed primarily for drinking water, fisheries and regulated boating rather than public bathing. Restrictions are in place to protect water quality, reduce contamination risk, and limit liability and safety concerns associated with a reservoir environment, such as sudden depth changes, boat traffic and cold-water hazards. Even on warm summer days, visitors should be aware that water temperatures can change rapidly and cold-water immersion carries the risk of hypothermia, which is another reason agencies discourage or prohibit swimming.