American Falls Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in American Falls Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in American Falls Reservoir today is 18°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 |
|---|---|---|---|
| SEP 14 | 19.6°C | 20.4°C | |
| SEP 15 | 18.8°C | 20.4°C | |
| SEP 16 | 18.2°C | 20.4°C | |
| SEP 17 | 17.6°C | 20.4°C | |
| SEP 18 | 17.8°C | 20.4°C | |
| SEP 19 | 18.3°C | 20.4°C | |
| SEP 20 | 18.3°C | 20.4°C | |
| SEP 21 | 18.0°C | 20.4°C | |
| SEP 22 | 20.4°C | 18.1°C | |
| SEP 23 | 20.4°C | 18.2°C | |
| SEP 24 | 20.4°C | 18.4°C | |
| SEP 25 | 20.4°C | 18.5°C | |
| SEP 26 | 20.4°C | 18.6°C | |
| SEP 27 | 20.4°C | 18.7°C | |
| SEP 28 | 20.4°C | 18.8°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 | 3°C | 6°C |
| February | 0°C | 3°C | 6°C |
| March | 1°C | 6°C | 11°C |
| April | 4°C | 8°C | 13°C |
| May | 9°C | 14°C | 20°C |
| June | 15°C | 19°C | 24°C |
| July | 19°C | 23°C | 28°C |
| August | 21°C | 25°C | 29°C |
| September | 16°C | 20°C | 25°C |
| October | 10°C | 14°C | 18°C |
| November | 4°C | 8°C | 11°C |
| December | 0°C | 3°C | 7°C |
American Falls Reservoir: Water Temperature by Location
American Falls Reservoir: Weather Forecast
September 21
September 22
September 23
September 24
September 25
Location & Local Information
American Falls Reservoir, located along the Snake River in southeastern Idaho, is one of the largest reservoirs in the state and plays a vital role in irrigation and recreation. Its water temperature varies significantly through the seasons because of the region’s continental climate and the reservoir’s large surface area. During winter months, the water can cool to around 34–39°F (1–4°C), and ice may form along sheltered sections. In spring, as air temperatures rise, the water warms gradually to about 46–57°F (8–14°C). By midsummer, the surface can reach 68–73°F (20–23°C), making this period the most comfortable for water-based recreation. In autumn, temperatures fall again toward 50–59°F (10–15°C).
Swimming is permitted in American Falls Reservoir, though conditions vary across the year. The best swimming months are typically July and August, when the water reaches its seasonal peak and the weather is warm and dry. Earlier in the year, even in late spring, the water remains quite cool, and swimmers may find it refreshing but brisk. The beaches near the city of American Falls offer gradual entry points and designated swimming areas, though visitors are advised to stay alert to fluctuating water levels and currents from reservoir management operations.