Flat River Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Flat River Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Flat River Reservoir today is 19.9°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. 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 | 12.9°C | 17.5°C | |
| JUN 4 | 13.6°C | 17.5°C | |
| JUN 5 | 16.0°C | 17.5°C | |
| JUN 6 | 17.0°C | 17.5°C | |
| JUN 7 | 18.8°C | 17.5°C | |
| JUN 8 | 19.2°C | 17.5°C | |
| JUN 10 | 19.9°C | 17.5°C | |
| JUN 11 | 17.5°C | 19.8°C | |
| JUN 12 | 17.5°C | 19.7°C | |
| JUN 13 | 17.5°C | 19.5°C | |
| JUN 14 | 17.5°C | 19.4°C | |
| JUN 15 | 17.5°C | 19.3°C | |
| JUN 16 | 17.5°C | 19.2°C | |
| JUN 17 | 17.5°C | 19.1°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 | 2°C | 4°C |
| February | 0°C | 2°C | 4°C |
| March | 0°C | 4°C | 7°C |
| April | 4°C | 10°C | 15°C |
| May | 11°C | 15°C | 20°C |
| June | 12°C | 18°C | 22°C |
| July | 21°C | 26°C | 31°C |
| August | 20°C | 25°C | 29°C |
| September | 18°C | 24°C | 29°C |
| October | 12°C | 16°C | 19°C |
| November | 4°C | 9°C | 13°C |
| December | 0°C | 3°C | 6°C |
Flat River Reservoir: Water Temperature by Location
Flat River Reservoir: Weather Forecast
June 9
June 10
June 11
June 12
Location & Local Information
Flat River Reservoir’s surface water temperatures follow the typical seasonal pattern for small New England impoundments. In spring the reservoir commonly ranges from about 45–65°F (7–18°C) as the water warms after ice-out. By summer, surface readings often reach roughly 70–80°F (21–27°C) on warm afternoons, while mid- to late-summer heat can push the shallowest areas toward the upper part of that range. In fall the surface cools again to roughly 50–68°F (10–20°C) and by winter the water near the surface approaches freezing, typically around 32–40°F (0–4°C) with ice forming in sustained cold spells. Deeper water remains cooler year-round, and temperature can vary with time of day, recent weather, and wind-driven mixing.
Swimming at Flat River Reservoir is possible in accessible areas during warmer months and many visitors swim there in summer, but local rules and safety considerations matter. Some parts of reservoirs are posted against swimming to protect drinking-water intakes, fragile shorelines, or for public-safety reasons such as boat traffic, underwater hazards, or cold-water shock outside summer. Water quality (including occasional algal blooms) can also affect whether swimming is advisable, so it’s best to heed posted signs and town or water-authority guidance before entering the water.