Hells Canyon Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Hells Canyon Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Hells Canyon Reservoir today is 28.9°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature is above 82°F (28°C). This is very warm water, which may feel almost hot to most people. Swimming in such conditions is perfect for those seeking relaxation and comfort in the water. These waters are often preferred for relaxation in hot weather, as the water temperature does not cool the body significantly. However, it is important to remember that in such warm waters, caution is necessary, as prolonged exposure without rest can lead to overheating. 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 4 | 29.3°C | 25.5°C | |
| AUG 5 | 29.1°C | 25.5°C | |
| AUG 6 | 29.1°C | 25.5°C | |
| AUG 7 | 29.2°C | 25.5°C | |
| AUG 8 | 29.3°C | 25.5°C | |
| AUG 9 | 29.4°C | 25.5°C | |
| AUG 10 | 29.0°C | 25.5°C | |
| AUG 11 | 29.0°C | 25.5°C | |
| AUG 12 | 25.5°C | 28.7°C | |
| AUG 13 | 25.5°C | 28.6°C | |
| AUG 14 | 25.5°C | 28.4°C | |
| AUG 15 | 25.5°C | 28.2°C | |
| AUG 16 | 25.5°C | 28.1°C | |
| AUG 17 | 25.5°C | 27.9°C | |
| AUG 18 | 25.5°C | 27.7°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 | 5°C | 10°C |
| February | 2°C | 6°C | 10°C |
| March | 4°C | 8°C | 12°C |
| April | 6°C | 10°C | 14°C |
| May | 8°C | 15°C | 21°C |
| June | 13°C | 18°C | 22°C |
| July | 17°C | 23°C | 29°C |
| August | 21°C | 26°C | 30°C |
| September | 19°C | 23°C | 26°C |
| October | 11°C | 15°C | 19°C |
| November | 8°C | 10°C | 13°C |
| December | 3°C | 6°C | 10°C |
Hells Canyon Reservoir: Water Temperature by Location
Hells Canyon Reservoir: Weather Forecast
August 12
August 13
August 14
August 15
August 16
Location & Local Information
Hells Canyon Reservoir, impounded on the Snake River along the Idaho–Oregon border, tends to have cool water year-round because of its depth and river inflow. Seasonal surface temperatures commonly range from about 40–55°F (4–13°C) in spring as snowmelt and runoff cool the basin, rise to roughly 60–70°F (15–21°C) in summer in sheltered shallows (with shallow coves occasionally reaching around 75°F / 24°C on very warm days), fall cooling back toward 50–60°F (10–16°C), and winter surface readings near 34–45°F (1–7°C) when cold air and reduced solar input dominate. Deeper water stays colder than surface readings, often several degrees lower, because of stratification and continual river exchange.
Swimming is generally permitted in the reservoir, but it is not a supervised or developed public beach in most spots, and several safety considerations affect whether people choose to swim. Cold-water shock and rapid loss of body heat are real risks at the typical temperatures, especially outside mid-summer, and strong currents, boat traffic, limited access points, steep drop-offs, and proximity to dam structures can make certain areas hazardous or restricted. Visitors should check local signs and operator guidance, use flotation aides or wetsuits in cooler conditions, avoid restricted zones near dams, and recognize there are usually no lifeguards on duty.