Alviela River — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in the Alviela River, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in the Alviela River today is 17.6°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 3 | 18.6°C | 20.0°C | |
| JUN 4 | 18.4°C | 20.0°C | |
| JUN 5 | 18.4°C | 20.0°C | |
| JUN 6 | 18.3°C | 20.0°C | |
| JUN 7 | 18.0°C | 20.0°C | |
| JUN 8 | 17.7°C | 20.0°C | |
| JUN 10 | 17.6°C | 20.0°C | |
| JUN 11 | 20.0°C | 17.7°C | |
| JUN 12 | 20.0°C | 17.8°C | |
| JUN 13 | 20.0°C | 18.0°C | |
| JUN 14 | 20.0°C | 18.1°C | |
| JUN 15 | 20.0°C | 18.2°C | |
| JUN 16 | 20.0°C | 18.3°C | |
| JUN 17 | 20.0°C | 18.4°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 | 6°C | 9°C | 12°C |
| February | 6°C | 9°C | 13°C |
| March | 9°C | 12°C | 15°C |
| April | 9°C | 13°C | 18°C |
| May | 10°C | 15°C | 20°C |
| June | 16°C | 20°C | 25°C |
| July | 18°C | 23°C | 27°C |
| August | 18°C | 23°C | 27°C |
| September | 18°C | 22°C | 27°C |
| October | 14°C | 18°C | 20°C |
| November | 10°C | 14°C | 18°C |
| December | 8°C | 11°C | 14°C |
Alviela River: Water Temperature by Location
Alviela River: Weather Forecast
June 9
June 10
June 11
June 12
June 13
June 14
Location & Local Information
Source:
• location Olhos d’Água do Alviela, Alcanena
• elevation 135 m (443 ft)
Mouth Tagus
• location near Vale de Figueira
• elevation 23 m (75 ft)
Length 51.16 km (31.79 mi)
The Alviela River (Portuguese: Rio Alviela) is influenced by karst springs in parts of its course, which tends to moderate and cool water temperatures. Seasonal water temperatures typically range from about 10–14 °C (50–57 °F) in winter, rise to roughly 12–18 °C (54–64 °F) in spring, and in shallower, sun-exposed stretches can reach 16–24 °C (61–75 °F) in summer. Autumn usually brings temperatures back toward the spring band, roughly 12–18 °C (54–64 °F). In spring-fed pools and deeper sinkhole zones the temperature is steadier and often on the cooler end of these ranges, while shallow, slow-flowing segments warm more in sunny months.
Swimming in the Rio Alviela is possible in various open stretches, but access and permissibility depend on local rules, land ownership and conservation designations. Some spring areas are protected for their ecological importance and may have restrictions; other spots present hazards such as cold shock from sudden temperature change, deep holes, submerged obstacles or stronger currents. For safety and legal reasons swimmers are advised to follow local signage, respect protected zones, and consider the cooler baseline temperatures—even in summer—that can affect comfort and endurance.