Alder Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Alder Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Alder Lake today is 19.7°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 24 | 20.3°C | 24.5°C | |
| AUG 25 | 19.9°C | 24.5°C | |
| AUG 26 | 19.9°C | 24.5°C | |
| AUG 27 | 19.9°C | 24.5°C | |
| AUG 28 | 20.0°C | 24.5°C | |
| AUG 29 | 20.0°C | 24.5°C | |
| AUG 30 | 20.0°C | 24.5°C | |
| AUG 31 | 19.7°C | 24.5°C | |
| SEP 1 | 21.5°C | 19.8°C | |
| SEP 2 | 21.5°C | 19.9°C | |
| SEP 3 | 21.5°C | 20.0°C | |
| SEP 4 | 21.5°C | 20.1°C | |
| SEP 5 | 21.5°C | 20.2°C | |
| SEP 6 | 21.5°C | 20.2°C | |
| SEP 7 | 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 | 3°C | 6°C |
| February | 2°C | 5°C | 8°C |
| March | 1°C | 6°C | 11°C |
| April | 4°C | 10°C | 15°C |
| May | 9°C | 15°C | 21°C |
| June | 12°C | 18°C | 24°C |
| July | 15°C | 23°C | 31°C |
| August | 19°C | 25°C | 30°C |
| September | 17°C | 22°C | 26°C |
| October | 12°C | 16°C | 20°C |
| November | 6°C | 11°C | 14°C |
| December | 4°C | 7°C | 9°C |
Alder Lake: Water Temperature by Location
Alder Lake: Weather Forecast
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September 6
Location & Local Information
Alder Lake, a reservoir on the Nisqually River in western Washington, experiences pronounced seasonal shifts in water temperature. In spring the surface commonly ranges from about 45 to 60 °F (7 to 16 °C) as snowmelt and cool air temperatures moderate warming. Summer brings the warmest surface conditions, typically around 60 to 75 °F (16 to 24 °C) on calm, sunny days, though deeper water remains much colder. In fall temperatures usually fall back into the 45 to 60 °F (7 to 16 °C) band as air cools, and in winter surface readings often drop into the mid-30s to mid-40s °F (2 to 7 °C), with the reservoir remaining cold below the surface year-round.
Swimming at Alder Lake is generally permitted and people do enter the water for recreation, but there are important safety considerations. Because it is a reservoir, water levels can change and currents or submerged hazards exist, and even in summer the water can produce cold shock or hypothermia in unprepared swimmers. There are limited lifeguarded areas, boat traffic is common, and local advisories about water quality or conditions should be checked before entering. For those who swim, staying near shore, wearing a personal flotation device when appropriate, and being mindful of temperature-related risks improves safety.