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 25.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 75°F (23°C) to 79°F (26°C). This is a very comfortable temperature for swimming, and many people can enjoy prolonged stays in the water without feeling cold. The water is pleasantly warm, making it ideal for relaxation and water sports. This temperature range is particularly popular among tourists, as it combines comfort and safety for health. 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 | 23.3°C | 26.0°C | |
| JUL 15 | 26.2°C | 26.0°C | |
| JUL 16 | 26.5°C | 26.0°C | |
| JUL 17 | 27.3°C | 26.0°C | |
| JUL 18 | 27.5°C | 26.0°C | |
| JUL 19 | 27.1°C | 26.0°C | |
| JUL 20 | 27.1°C | 26.0°C | |
| JUL 21 | 25.0°C | 26.0°C | |
| JUL 22 | 26.0°C | 25.5°C | |
| JUL 23 | 26.0°C | 25.6°C | |
| JUL 24 | 26.0°C | 25.6°C | |
| JUL 25 | 26.0°C | 25.6°C | |
| JUL 26 | 26.0°C | 25.6°C | |
| JUL 27 | 26.0°C | 25.7°C | |
| JUL 28 | 26.0°C | 25.7°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
July 22
July 23
July 24
July 25
July 26
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.