Wachusett Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Wachusett Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Wachusett Reservoir today is 15.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 60°F (15°C) to 65°F (18°C). The water is comfortable for most people, making it an ideal range for water sports enthusiasts. The temperature does not cause significant discomfort, and swimming will be pleasant for the majority. However, it's important to remember that prolonged exposure to the water can still lead to cooling, so it's essential to monitor the time spent in the water, especially for children or elderly people. 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 |
|---|---|---|---|
| OCT 5 | 18.5°C | 15.5°C | |
| OCT 6 | 17.5°C | 15.5°C | |
| OCT 7 | 18.1°C | 15.5°C | |
| OCT 8 | 17.3°C | 15.5°C | |
| OCT 9 | 16.1°C | 15.5°C | |
| OCT 10 | 16.8°C | 15.5°C | |
| OCT 11 | 16.5°C | 15.5°C | |
| OCT 12 | 16.2°C | 15.5°C | |
| OCT 13 | 15.5°C | 15.5°C | |
| OCT 14 | 15.5°C | 15.5°C | |
| OCT 15 | 15.5°C | 15.5°C | |
| OCT 16 | 15.5°C | 15.5°C | |
| OCT 17 | 15.5°C | 15.5°C | |
| OCT 18 | 15.5°C | 15.5°C | |
| OCT 19 | 15.5°C | 15.5°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 | 5°C |
| February | 0°C | 2°C | 4°C |
| March | 0°C | 3°C | 6°C |
| April | 3°C | 7°C | 12°C |
| May | 9°C | 14°C | 19°C |
| June | 14°C | 18°C | 21°C |
| July | 20°C | 24°C | 29°C |
| August | 22°C | 24°C | 27°C |
| September | 19°C | 22°C | 25°C |
| October | 12°C | 16°C | 19°C |
| November | 4°C | 9°C | 12°C |
| December | 1°C | 3°C | 6°C |
Wachusett Reservoir: Water Temperature by Location
Wachusett Reservoir: Weather Forecast
October 13
October 14
October 15
October 16
October 17
Location & Local Information
Wachusett Reservoir, a large impoundment that serves as a regional drinking water source in central Massachusetts, shows marked seasonal variation in surface temperatures. In winter the surface commonly sits near freezing, roughly 32–40°F (0–4°C). Spring warming brings surface values into the 40–60°F range (4–16°C) as stratification begins. During summer, surface temperatures on warm, calm days typically reach about 65–75°F (18–24°C), though shallow bays can be a few degrees warmer and deeper water remains substantially cooler. In autumn the surface usually falls back into the 45–60°F band (7–16°C) as the reservoir mixes and cools. Internal temperature layering means deeper water remains much colder year-round, so thermal conditions vary with depth and weather.
Swimming in Wachusett Reservoir is not permitted because it is part of the municipal water supply and direct-contact recreation is restricted to protect water quality and public health. Rules enforced by the water authority and watershed management agencies prohibit bathing and unmanaged wading; signage and patrols reflect those limits. Beyond regulatory reasons, cold temperatures even in summer and variable depths create safety risks such as cold shock and currents, reinforcing the prohibition on open swimming despite the reservoir’s scenic setting.