Sunapee Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Sunapee Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Sunapee Lake today is 20.9°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 23 | 19.7°C | 17.1°C | |
| JUN 24 | 19.8°C | 17.1°C | |
| JUN 25 | 19.8°C | 17.1°C | |
| JUN 26 | 19.8°C | 17.1°C | |
| JUN 27 | 20.0°C | 17.1°C | |
| JUN 28 | 20.1°C | 17.1°C | |
| JUN 29 | 20.0°C | 17.1°C | |
| JUN 30 | 20.0°C | 17.1°C | |
| JUL 1 | 25.0°C | 21.1°C | |
| JUL 2 | 25.0°C | 21.3°C | |
| JUL 3 | 25.0°C | 21.5°C | |
| JUL 4 | 25.0°C | 21.7°C | |
| JUL 5 | 25.0°C | 21.9°C | |
| JUL 6 | 25.0°C | 22.1°C | |
| JUL 7 | 25.0°C | 22.3°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 | 0°C | 8°C | 15°C |
| February | 1°C | 7°C | 13°C |
| March | 0°C | 7°C | 13°C |
| April | 1°C | 9°C | 16°C |
| May | 8°C | 14°C | 19°C |
| June | 13°C | 17°C | 22°C |
| July | 19°C | 25°C | 31°C |
| August | 20°C | 23°C | 26°C |
| September | 18°C | 21°C | 24°C |
| October | 10°C | 15°C | 19°C |
| November | 3°C | 7°C | 11°C |
| December | 0°C | 4°C | 7°C |
Sunapee Lake: Water Temperature by Location
Sunapee Lake: Weather Forecast
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July 6
Location & Local Information
Lake Sunapee’s water temperature varies considerably through the year and with depth. In the summer months surface temperatures commonly warm to roughly 70–75°F (21–24°C), and on particularly hot, calm days can approach the upper 70s°F (about 25–26°C). Spring brings a rapid cool-down from cold runoff, with surface readings often in the 40s–60°F range (4–16°C) until the lake stratifies, while fall sees a steady decline back into the 50s–60s°F (10–18°C). Below the summer thermocline the water remains much cooler; mid-depth and deep areas can stay in the 40s–50s°F (7–13°C) even in July and August. In winter the lake can freeze or hold near-freezing temperatures, with water close to 32–39°F (0–4°C) under ice.
Swimming is permitted in Lake Sunapee, particularly at designated public and park beaches that are maintained for recreational use and often staffed with seasonal lifeguards from late spring through early fall. These sites are chosen for safer entry points and monitored water quality, but swimmers should be aware that water can feel brisk and that deeper or off-shore areas remain cold year-round, presenting a risk of rapid cooling or hypothermia. Ice swimming is strongly discouraged except where officially organized and supervised because of thin ice and cold-water hazards.