Thermalito Afterbay Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Thermalito Afterbay Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Thermalito Afterbay Lake today is 18.2°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 |
|---|---|---|---|
| OCT 5 | 17.6°C | 17.5°C | |
| OCT 6 | 17.9°C | 17.5°C | |
| OCT 7 | 18.1°C | 17.5°C | |
| OCT 8 | 18.0°C | 17.5°C | |
| OCT 9 | 18.0°C | 17.5°C | |
| OCT 10 | 17.9°C | 17.5°C | |
| OCT 11 | 18.2°C | 17.5°C | |
| OCT 12 | 18.6°C | 17.5°C | |
| OCT 13 | 17.5°C | 18.2°C | |
| OCT 14 | 17.5°C | 18.1°C | |
| OCT 15 | 17.5°C | 18.1°C | |
| OCT 16 | 17.5°C | 18.1°C | |
| OCT 17 | 17.5°C | 18.0°C | |
| OCT 18 | 17.5°C | 18.0°C | |
| OCT 19 | 17.5°C | 18.0°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 | 1°C | 7°C | 12°C |
| February | 5°C | 9°C | 13°C |
| March | 6°C | 13°C | 20°C |
| April | 10°C | 15°C | 20°C |
| May | 14°C | 19°C | 25°C |
| June | 21°C | 24°C | 28°C |
| July | 22°C | 26°C | 31°C |
| August | 22°C | 27°C | 32°C |
| September | 20°C | 24°C | 28°C |
| October | 13°C | 18°C | 22°C |
| November | 9°C | 14°C | 18°C |
| December | 7°C | 10°C | 13°C |
Thermalito Afterbay Lake: Water Temperature by Location
Thermalito Afterbay Lake: Weather Forecast
October 13
October 14
October 15
October 16
October 17
Location & Local Information
Thermalito Afterbay is a shallow, managed reservoir near Oroville whose surface water temperatures vary with season and weather. In winter the surface typically ranges from about 45–55°F (7–13°C). Spring temperatures commonly rise into the 50–68°F (10–20°C) band as air warms. In summer the shallow water can reach roughly 65–80°F (18–27°C) at the surface on warm, calm days, while fall temperatures usually cool back into the 55–70°F (13–21°C) range. Deeper pockets and areas near outlets or inflows can be notably colder year‑round, and shallow shoals may heat more quickly in hot spells.
Swimming at Thermalito Afterbay is generally discouraged and often effectively limited by local conditions rather than promoted as a formal swim beach. The site supports heavy boating, windsurfing and water‑management operations, and there are potential hazards such as boat traffic, submerged structure, variable currents from releases, and occasional water‑quality or algal‑bloom concerns; lifeguards are typically not provided. For safety, many people choose swimming areas that are designated and supervised elsewhere, while the Afterbay is more commonly used for boating and shoreline recreation.