Hernani — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Hernani, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Hernani today is 20°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 |
|---|---|---|---|
| SEP 13 | 20.8°C | 17.8°C | |
| SEP 14 | 20.4°C | 17.8°C | |
| SEP 15 | 20.5°C | 17.8°C | |
| SEP 16 | 20.6°C | 17.8°C | |
| SEP 17 | 20.7°C | 17.8°C | |
| SEP 18 | 21.1°C | 17.8°C | |
| SEP 19 | 19.5°C | 17.8°C | |
| SEP 20 | 19.7°C | 17.8°C | |
| SEP 21 | 17.8°C | 19.9°C | |
| SEP 22 | 17.8°C | 19.8°C | |
| SEP 23 | 17.8°C | 19.7°C | |
| SEP 24 | 17.8°C | 19.6°C | |
| SEP 25 | 17.8°C | 19.5°C | |
| SEP 26 | 17.8°C | 19.3°C | |
| SEP 27 | 17.8°C | 19.2°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 | 7°C | 11°C |
| February | 4°C | 8°C | 12°C |
| March | 7°C | 10°C | 13°C |
| April | 9°C | 13°C | 16°C |
| May | 9°C | 15°C | 21°C |
| June | 13°C | 19°C | 24°C |
| July | 14°C | 20°C | 26°C |
| August | 15°C | 20°C | 26°C |
| September | 13°C | 18°C | 23°C |
| October | 10°C | 14°C | 17°C |
| November | 8°C | 13°C | 17°C |
| December | 4°C | 8°C | 12°C |
Hernani: Weather Forecast
September 21
September 22
September 23
September 24
September 25
September 26
Location & Local Information
Hernani, a town in the Basque Country near San Sebastián, sits in a green, hilly landscape crossed by the Urumea river and small reservoirs and ponds in the surrounding countryside. Water temperatures in inland lakes and slow-flowing stretches around Hernani follow a maritime-influenced pattern: in winter surface temperatures commonly sit around 6–10 °C (43–50 °F), spring brings warming to roughly 9–16 °C (48–61 °F), peak summer temperatures generally reach 16–22 °C (61–72 °F) in sheltered waters, and autumn sees a gradual cooling to approximately 12–18 °C (54–64 °F). Occasional warm spells can push shallow spots slightly higher, but long periods above 24 °C (75 °F) are uncommon.
Swimming in lakes and reservoirs close to Hernani is possible in summer when temperatures are highest, but it is not always officially permitted or supervised. Some reservoirs are protected as water sources or have safety restrictions, and water quality can vary after heavy rain, so local signage and municipal rules must be checked before entering the water. Where bathing is allowed, conditions tend to be cooler than coastal beaches, so swimmers should be prepared for brisk water and uneven entry. For organised, lifeguarded swimming most people use nearby coastal beaches rather than inland lakes.