Viana do Castelo Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Viana do Castelo, Norte Region, Portugal. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Let's now guide you through the details for a complete overview.

Viana do Castelo is known for its substantial rainfall, with annual precipitation reaching 1649 mm (65 in). While the overall climate is wet, there are notable seasonal patterns that create interesting contrasts, as demonstrated in our graph below.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

Significant seasonal changes in precipitation occur throughout the year. During the wettest month, November receives substantial rainfall, averaging 225 mm (8.9 in) of precipitation, recorded across 17 rainy days.

In contrast, the driest month, July brings less rainfall, with 29 mm (1.1 in) over 7 rainy days.

November, the wettest month, has a maximum daytime temperature of 17°C (63°F). The city receives 138 hours of sunshine in this period. During the driest month July you can expect a temperature of 23°C (73°F). For more detailed insights into the city's temperatures, visit our Viana do Castelo Temperature page.

Viana do Castelo's average annual precipitation is 1649 mm (65 in). Let's compare this to some popular worldwide tourist destinations:

The climate in San Francisco, USA, is influenced by coastal weather, with 469 mm (18 in) of rainfall mostly during the winter months.

In Seoul, South Korea, the average annual precipitation is 1237 mm (49 in), with most rain falling during the summer monsoon season.

In Brisbane, Australia, the annual precipitation is 979 mm (39 in), making it wetter than Sydney.

Singapore, situated near the equator, gets 2581 mm (102 in) of rainfall annually, with no distinct dry season and consistent monthly precipitation.

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Precipitation has a very strong role in determining the local climate and ecosystem:

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm (15 inches) wide and 20 cm (7.9 inches) thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA, over 31.5 meters (103 feet) fell during the winter of 1972.

For more detailed information about Viana do Castelo's weather, including sunshine hours, humidity levels, and temperature data, visit our Viana do Castelo Climate page.