Foster Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Foster Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Foster Lake today is 19.6°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 |
|---|---|---|---|
| AUG 4 | 19.8°C | 21.5°C | |
| AUG 5 | 19.6°C | 21.5°C | |
| AUG 6 | 19.8°C | 21.5°C | |
| AUG 7 | 21.2°C | 21.5°C | |
| AUG 8 | 21.3°C | 21.5°C | |
| AUG 9 | 21.1°C | 21.5°C | |
| AUG 10 | 21.2°C | 21.5°C | |
| AUG 11 | 21.0°C | 21.5°C | |
| AUG 12 | 21.5°C | 19.7°C | |
| AUG 13 | 21.5°C | 19.8°C | |
| AUG 14 | 21.5°C | 19.9°C | |
| AUG 15 | 21.5°C | 20.0°C | |
| AUG 16 | 21.5°C | 20.1°C | |
| AUG 17 | 21.5°C | 20.2°C | |
| AUG 18 | 21.5°C | 20.3°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 | 4°C | 9°C |
| February | 0°C | 4°C | 9°C |
| March | 1°C | 6°C | 11°C |
| April | 7°C | 11°C | 15°C |
| May | 11°C | 16°C | 21°C |
| June | 11°C | 17°C | 23°C |
| July | 13°C | 20°C | 26°C |
| August | 16°C | 22°C | 27°C |
| September | 14°C | 18°C | 22°C |
| October | 10°C | 12°C | 15°C |
| November | 4°C | 8°C | 11°C |
| December | 4°C | 7°C | 11°C |
Foster Lake: Water Temperature by Location
Foster Lake: Weather Forecast
August 12
August 13
August 14
August 15
August 16
Location & Local Information
Foster Lake (Foster Reservoir) in Oregon experiences noticeable seasonal variation in water temperature. In winter the surface often sits around 35–45°F (2–7°C), while spring temperatures typically climb into the 45–60°F (7–16°C) range as snowmelt and river inflows warm. By summer, surface readings commonly reach about 60–75°F (15–24°C) on warm afternoons, though cooler conditions persist at depth because the reservoir stratifies; deeper water can remain much colder year-round. Early fall temperatures generally fall back toward the 55–70°F (13–21°C) range as air temperatures cool and mixing increases.
Swimming at Foster Lake is permitted and commonly practiced from beaches and shorelines at county and private recreation areas, but conditions influence whether it’s comfortable or advisable. Designated swim spots may have better access and fewer boats, but there are usually no lifeguards, and cold water, sudden drop-offs, submerged hazards, and boat traffic present risks. Because surface temperatures can still be chilly outside midsummer, swimmers should be cautious about cold shock and hypothermia, choose life jackets for weaker swimmers, and follow posted rules at parks and boat ramps to stay safe.