San Juan Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in San Juan Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in San Juan Reservoir today is 19.2°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 4 | 20.7°C | 18.0°C | |
| OCT 5 | 20.3°C | 18.0°C | |
| OCT 6 | 20.1°C | 18.0°C | |
| OCT 7 | 20.0°C | 18.0°C | |
| OCT 8 | 19.8°C | 18.0°C | |
| OCT 9 | 19.9°C | 18.0°C | |
| OCT 10 | 19.7°C | 18.0°C | |
| OCT 12 | 18.0°C | 19.1°C | |
| OCT 13 | 18.0°C | 19.1°C | |
| OCT 14 | 18.0°C | 19.0°C | |
| OCT 15 | 18.0°C | 19.0°C | |
| OCT 16 | 18.0°C | 18.9°C | |
| OCT 17 | 18.0°C | 18.8°C | |
| OCT 18 | 18.0°C | 18.8°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 | 4°C | 8°C | 11°C |
| February | 6°C | 10°C | 13°C |
| March | 7°C | 11°C | 14°C |
| April | 9°C | 14°C | 20°C |
| May | 13°C | 19°C | 25°C |
| June | 21°C | 28°C | 34°C |
| July | 21°C | 26°C | 32°C |
| August | 22°C | 27°C | 33°C |
| September | 20°C | 25°C | 30°C |
| October | 13°C | 18°C | 21°C |
| November | 8°C | 13°C | 17°C |
| December | 6°C | 11°C | 14°C |
San Juan Reservoir: Water Temperature by Location
San Juan Reservoir: Weather Forecast
October 11
October 12
October 13
October 14
October 15
Location & Local Information
The Embalse de San Juan, a reservoir near Madrid, experiences a wide range of water temperatures through the year. In winter the surface typically cools to around 6–12 °C (43–54 °F), while spring brings a gradual rise to roughly 12–18 °C (54–64 °F). Summer is when the reservoir is warmest, with surface temperatures commonly reaching 20–27 °C (68–81 °F) and occasionally higher during heat waves; shallow bays warm faster than deeper areas where temperatures remain lower. In autumn the water cools again, often ranging from about 12–20 °C (54–68 °F). These values vary with weather, wind, inflows and the depth of the bathing spot, so observed temperatures at popular beaches can differ from measurements taken in deeper channels.
Swimming at Embalse de San Juan is generally allowed and the reservoir is a well-known local spot for bathing, especially in designated beaches where authorities monitor water quality and provide seasonal lifeguards. Restrictions or temporary bans can be imposed if tests show contamination, algal blooms, or poor visibility, and some areas are limited because of boating and water sports. Visitors should choose official swimming zones, heed posted warnings and be mindful of sudden depth changes and boat traffic even when bathing is permitted.