Tongue River Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Tongue River Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Tongue River Reservoir today is 19.3°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. 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 | 20.5°C | 18.9°C | |
| SEP 15 | 19.8°C | 18.9°C | |
| SEP 16 | 20.8°C | 18.9°C | |
| SEP 17 | 18.9°C | 18.9°C | |
| SEP 18 | 18.1°C | 18.9°C | |
| SEP 19 | 18.2°C | 18.9°C | |
| SEP 20 | 18.7°C | 18.9°C | |
| SEP 21 | 19.3°C | 18.9°C | |
| SEP 22 | 18.9°C | 19.3°C | |
| SEP 23 | 18.9°C | 19.3°C | |
| SEP 24 | 18.9°C | 19.2°C | |
| SEP 25 | 18.9°C | 19.2°C | |
| SEP 26 | 18.9°C | 19.2°C | |
| SEP 27 | 18.9°C | 19.2°C | |
| SEP 28 | 18.9°C | 19.2°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 | 5°C |
| February | 1°C | 4°C | 7°C |
| March | 1°C | 5°C | 9°C |
| April | 0°C | 7°C | 15°C |
| May | 4°C | 12°C | 21°C |
| June | 11°C | 16°C | 21°C |
| July | 16°C | 22°C | 29°C |
| August | 18°C | 23°C | 29°C |
| September | 14°C | 19°C | 24°C |
| October | 7°C | 13°C | 18°C |
| November | 3°C | 7°C | 9°C |
| December | 2°C | 4°C | 7°C |
Tongue River Reservoir: Water Temperature by Location
Tongue River Reservoir: Weather Forecast
September 21
September 22
September 23
September 24
September 25
Location & Local Information
Tongue River Reservoir in southeastern Montana typically experiences cool to cold water much of the year because of the region’s continental climate. In winter months the surface often approaches freezing (around 32–36°F / 0–2°C) and the lake can ice over. Spring temperatures usually rise slowly, commonly ranging from about 40–55°F (4–13°C) as runoff and cooler air keep the water chilly. Peak summer surface temperatures in July and August are generally the warmest, often reaching roughly 65–78°F (18–26°C) on warm, sunny days, though deeper water remains cooler. In autumn the surface cools again, commonly falling between 45–65°F (7–18°C) as air temperatures drop and mixing increases.
Swimming at Tongue River Reservoir is generally permitted and the area is used for recreational swimming in summer because surface temperatures can be comfortable for short swims. However, swimmers should exercise caution: there are commonly no lifeguards, water can be deceptively cold below the surface, and hazards such as sudden drop-offs, boat traffic, and submerged debris exist. In shoulder seasons and winter, cold-water shock and thin ice make swimming unsafe. Visitors are advised to check local conditions, use flotation as needed, and follow posted rules for safe recreation.