Cottage Grove Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Cottage Grove Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Cottage Grove Lake today is 16.9°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 |
|---|---|---|---|
| JUN 23 | 18.4°C | 18.5°C | |
| JUN 24 | 18.6°C | 18.5°C | |
| JUN 25 | 18.8°C | 18.5°C | |
| JUN 26 | 18.7°C | 18.5°C | |
| JUN 27 | 18.6°C | 18.5°C | |
| JUN 28 | 18.0°C | 18.5°C | |
| JUN 29 | 17.7°C | 18.5°C | |
| JUN 30 | 17.2°C | 18.5°C | |
| JUL 1 | 21.5°C | 17.1°C | |
| JUL 2 | 21.5°C | 17.4°C | |
| JUL 3 | 21.5°C | 17.6°C | |
| JUL 4 | 21.5°C | 17.8°C | |
| JUL 5 | 21.5°C | 18.1°C | |
| JUL 6 | 21.5°C | 18.3°C | |
| JUL 7 | 21.5°C | 18.5°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 | 7°C |
| February | 0°C | 4°C | 8°C |
| March | 1°C | 6°C | 10°C |
| April | 9°C | 12°C | 15°C |
| May | 12°C | 17°C | 21°C |
| June | 13°C | 19°C | 23°C |
| July | 17°C | 22°C | 26°C |
| August | 17°C | 22°C | 27°C |
| September | 18°C | 20°C | 22°C |
| October | 10°C | 14°C | 18°C |
| November | 4°C | 8°C | 13°C |
| December | 4°C | 7°C | 11°C |
Cottage Grove Lake: Water Temperature by Location
Cottage Grove Lake: Weather Forecast
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Location & Local Information
Cottage Grove Lake is a managed reservoir in Oregon’s Willamette Valley whose surface temperatures change markedly with the seasons. In spring (March–May) surface water typically ranges from roughly 45–60°F (7–16°C) as runoff cools the basin. Summer (June–August) brings the warmest conditions, with surface temperatures commonly between about 60–75°F (16–24°C) on sunny days, though deeper water remains cooler. In fall (September–November) temperatures generally decline to roughly 50–65°F (10–18°C), and winter (December–February) surface readings often sit in the 40–50°F range (4–10°C). These values are approximate; actual temperatures vary by weather, depth, and time of day.
Swimming at Cottage Grove Lake is permitted in day‑use and beach areas because the reservoir is managed for multiple recreational uses, including swimming, boating and fishing. However, there are typically no lifeguards, and local rules and posted advisories should be followed. Water quality conditions such as elevated bacteria or harmful algal blooms can occur seasonally, and cold water temperatures—even in summer below the surface—present a risk of cold‑water shock or hypothermia. Visitors are advised to check current park notices, swim in designated zones, wear flotation for open‑water swimming, and avoid entering the water during posted advisories.