Holter Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Holter Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Holter Lake today is 21.7°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 |
|---|---|---|---|
| AUG 24 | 21.7°C | 20.7°C | |
| AUG 25 | 21.5°C | 20.7°C | |
| AUG 26 | 21.4°C | 20.7°C | |
| AUG 27 | 20.7°C | 20.7°C | |
| AUG 28 | 20.6°C | 20.7°C | |
| AUG 29 | 20.6°C | 20.7°C | |
| AUG 30 | 20.9°C | 20.7°C | |
| AUG 31 | 21.9°C | 20.7°C | |
| SEP 1 | 16.5°C | 21.4°C | |
| SEP 2 | 16.5°C | 21.2°C | |
| SEP 3 | 16.5°C | 20.9°C | |
| SEP 4 | 16.5°C | 20.7°C | |
| SEP 5 | 16.5°C | 20.4°C | |
| SEP 6 | 16.5°C | 20.1°C | |
| SEP 7 | 16.5°C | 19.9°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 | 11°C |
| May | 4°C | 11°C | 18°C |
| June | 9°C | 14°C | 18°C |
| July | 15°C | 20°C | 25°C |
| August | 17°C | 21°C | 25°C |
| September | 13°C | 17°C | 20°C |
| October | 4°C | 10°C | 16°C |
| November | 3°C | 7°C | 10°C |
| December | 1°C | 6°C | 10°C |
Holter Lake: Water Temperature by Location
Holter Lake: Weather Forecast
September 1
September 2
September 3
September 4
September 5
September 6
Location & Local Information
Holter Lake, a reservoir on the Missouri River in Montana, exhibits pronounced seasonal variation in surface water temperature. In spring (April–May) surface temperatures commonly run about 40–60°F (4–15°C) as snowmelt and cold inflows dominate. Early summer (June) typically warms into the 60–70°F range (15–21°C), while peak summer months (July–August) can bring surface readings around 70–78°F (21–26°C) in shallower bays and sun-warmed areas. By fall (September–October) the lake cools again to roughly 50–65°F (10–18°C). In winter the reservoir often approaches freezing, with surface temperatures near 32–40°F (0–4°C) and ice forming in colder years. Temperatures vary with depth, flow from the dam, and exposure to sun and wind, so localized conditions may differ from these broad seasonal ranges.
Swimming is generally permitted at Holter Lake in public recreation zones and at shoreline access points, but there are important safety considerations. No lifeguards are typically on duty, and cold water, sudden depth changes, submerged obstacles, boat traffic and stronger currents near the dam increase risk. Seasonal fluctuations and drawdowns can expose hazards, and winter conditions with near-freezing water or ice make immersion dangerous. Visitors are advised to choose established swimming areas, wear flotation when appropriate, and heed posted signs and local guidance before entering the water.