Ennis Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Ennis Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Ennis Lake today is 9.6°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
❌ As of today, the minimum water temperature ranges from 47°F (8°C) to 50°F (10°C). This is still cool water, suitable only for experienced swimmers or those accustomed to cold water. Swimming in such conditions is possible, but not recommended for prolonged periods. Extra caution should be taken during extended exposure, as the cold water can cause heat loss and lead to hypothermia. For added comfort, special clothing can be used. 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 | 9.3°C | 9.5°C | |
| OCT 6 | 9.6°C | 9.5°C | |
| OCT 7 | 9.6°C | 9.5°C | |
| OCT 8 | 9.5°C | 9.5°C | |
| OCT 9 | 9.1°C | 9.5°C | |
| OCT 10 | 8.4°C | 9.5°C | |
| OCT 11 | 8.7°C | 9.5°C | |
| OCT 12 | 9.9°C | 9.5°C | |
| OCT 13 | 9.5°C | 9.6°C | |
| OCT 14 | 9.5°C | 9.6°C | |
| OCT 15 | 9.5°C | 9.6°C | |
| OCT 16 | 9.5°C | 9.6°C | |
| OCT 17 | 9.5°C | 9.6°C | |
| OCT 18 | 9.5°C | 9.6°C | |
| OCT 19 | 9.5°C | 9.6°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 | 6°C |
| February | 1°C | 4°C | 7°C |
| March | 1°C | 5°C | 9°C |
| April | 0°C | 5°C | 10°C |
| May | 4°C | 10°C | 17°C |
| June | 9°C | 13°C | 18°C |
| July | 14°C | 19°C | 25°C |
| August | 17°C | 20°C | 24°C |
| September | 13°C | 16°C | 20°C |
| October | 4°C | 10°C | 15°C |
| November | 0°C | 6°C | 10°C |
| December | 2°C | 5°C | 7°C |
Ennis Lake: Water Temperature by Location
Ennis Lake: Weather Forecast
October 13
October 14
October 15
October 16
October 17
Location & Local Information
Ennis Lake, a reservoir on the Madison River in southwestern Montana, stays relatively cool through much of the year because of its elevation and river-fed source. Typical seasonal surface temperatures are roughly 35–50°F (2–10°C) in spring as snowmelt and runoff dominate, warming to about 50–60°F (10–16°C) in early summer. The warmest period is usually mid- to late summer, when surface readings commonly reach 60–70°F (15–21°C) and on hot spells may approach 70–75°F (21–24°C). By fall the water cools again to roughly 40–55°F (4–13°C), and in winter the lake can approach freezing, about 32–36°F (0–2°C), with ice possible depending on conditions.
Swimming is generally allowed in Ennis Lake because it is a public reservoir, but opportunities are limited by the consistently cool temperatures, a short comfortable season, and safety considerations. Even in summer, colder depths and swift inflows can produce hypothermia risk, and there is boat traffic and occasional currents near the dam and inlets. As a result, most recreational swimming occurs only during the warmest weeks, and swimmers are advised to be cautious and mindful of changing conditions rather than assuming prolonged warm-water swimming is available.