Bynum Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Bynum Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Bynum Reservoir today is 15.9°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 |
|---|---|---|---|
| JUN 3 | 14.7°C | 14.5°C | |
| JUN 4 | 14.6°C | 14.5°C | |
| JUN 5 | 14.6°C | 14.5°C | |
| JUN 6 | 15.5°C | 14.5°C | |
| JUN 7 | 15.8°C | 14.5°C | |
| JUN 8 | 15.8°C | 14.5°C | |
| JUN 11 | 14.5°C | 15.8°C | |
| JUN 12 | 14.5°C | 15.8°C | |
| JUN 13 | 14.5°C | 15.7°C | |
| JUN 14 | 14.5°C | 15.6°C | |
| JUN 15 | 14.5°C | 15.6°C | |
| JUN 16 | 14.5°C | 15.5°C | |
| JUN 17 | 14.5°C | 15.4°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 | 4°C | 6°C |
| February | 0°C | 4°C | 7°C |
| March | 1°C | 5°C | 9°C |
| April | 0°C | 4°C | 8°C |
| May | 4°C | 9°C | 15°C |
| June | 9°C | 15°C | 20°C |
| July | 16°C | 19°C | 22°C |
| August | 17°C | 19°C | 22°C |
| September | 13°C | 17°C | 20°C |
| October | 4°C | 10°C | 16°C |
| November | 2°C | 6°C | 10°C |
| December | 1°C | 5°C | 7°C |
Bynum Reservoir: Water Temperature by Location
Bynum Reservoir: Weather Forecast
June 9
June 10
June 11
June 12
Location & Local Information
Lake of Bynum Reservoir in central Montana typically follows the seasonal temperature patterns of shallow inland reservoirs. In spring, surface temperatures commonly range from about 40–60°F (4–16°C) as snowmelt and cool air keep the water chilly. Summer brings the warmest conditions, with surface readings often between 60–75°F (15–24°C) on warm afternoons; however, deeper water remains noticeably cooler throughout the year. In autumn the surface cools again to roughly 45–60°F (7–16°C) as air temperatures drop, and in winter the reservoir can approach freezing at or near 32°F (0°C), with ice cover possible depending on local conditions. These values are approximate averages and can vary with weather, depth, and inflow.
Swimming is generally possible at rural Montana reservoirs during the warmest weeks of summer because surface temperatures can reach levels comfortable for short-term immersion, but specific allowances depend on landowner and county rules and any posted advisories. Even when swimming is permitted, users should be cautious about cold shock from lower-than-expected water temperatures, lack of lifeguards, underwater hazards, and variable water quality. For safe recreation, check local signage and conditions before entering the water and avoid extended exposure in temperatures below the mid-60s°F (around 18°C).