Climate and Average Weather Year Round in Viana do Castelo PortugalIn Viana do Castelo, the summers are comfortable, dry, and mostly clear and the winters are cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 46°F to 75°F and is rarely below 38°F or above 85°F. Based on the tourism score, the best time of year to visit Viana do Castelo for warm-weather activities is from mid June to early September. Average Temperature in Viana do CasteloThe warm season lasts for 3.2 months, from June 16 to September 23, with an average daily high temperature above 71°F. The hottest month of the year in Viana do Castelo is August, with an average high of 74°F and low of 61°F. The cool season lasts for 3.5 months, from November 22 to March 5, with an average daily high temperature below 60°F. The coldest month of the year in Viana do Castelo is January, with an average low of 46°F and high of 57°F.
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day. Manukau City, New Zealand (12,070 miles away) is the far-away foreign place with temperatures most similar to Viana do Castelo (view comparison). CloudsIn Viana do Castelo, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year. The clearer part of the year in Viana do Castelo begins around June 7 and lasts for 3.2 months, ending around September 15. The clearest month of the year in Viana do Castelo is July, during which on average the sky is clear, mostly clear, or partly cloudy 82% of the time. The cloudier part of the year begins around September 15 and lasts for 8.8 months, ending around June 7. The cloudiest month of the year in Viana do Castelo is December, during which on average the sky is overcast or mostly cloudy 56% of the time.
PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Viana do Castelo varies significantly throughout the year. The wetter season lasts 8.1 months, from September 25 to May 28, with a greater than 24% chance of a given day being a wet day. The month with the most wet days in Viana do Castelo is November, with an average of 11.4 days with at least 0.04 inches of precipitation. The drier season lasts 3.9 months, from May 28 to September 25. The month with the fewest wet days in Viana do Castelo is July, with an average of 2.3 days with at least 0.04 inches of precipitation. Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Viana do Castelo is November, with an average of 11.4 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 41% on October 28.
RainfallTo show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Viana do Castelo experiences extreme seasonal variation in monthly rainfall. Rain falls throughout the year in Viana do Castelo. The month with the most rain in Viana do Castelo is December, with an average rainfall of 5.4 inches. The month with the least rain in Viana do Castelo is July, with an average rainfall of 0.5 inches.
SunThe length of the day in Viana do Castelo varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 9 minutes of daylight; the longest day is June 20, with 15 hours, 12 minutes of daylight.
The earliest sunrise is at 6:00 AM on June 14, and the latest sunrise is 2 hours, 2 minutes later at 8:02 AM on January 4. The earliest sunset is at 5:04 PM on December 8, and the latest sunset is 4 hours, 9 minutes later at 9:14 PM on June 26. Daylight saving time (DST) is observed in Viana do Castelo during 2024, starting in the spring on March 31, lasting 6.9 months, and ending in the fall on October 27. The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation. MoonThe figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. HumidityWe base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night. Viana do Castelo experiences some seasonal variation in the perceived humidity. The muggier period of the year lasts for 3.4 months, from June 21 to October 3, during which time the comfort level is muggy, oppressive, or miserable at least 3% of the time. The month with the most muggy days in Viana do Castelo is August, with 3.4 days that are muggy or worse. The least muggy day of the year is February 23, when muggy conditions are essentially unheard of.
WindThis section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages. The average hourly wind speed in Viana do Castelo experiences mild seasonal variation over the course of the year. The windier part of the year lasts for 6.4 months, from October 23 to May 5, with average wind speeds of more than 7.8 miles per hour. The windiest month of the year in Viana do Castelo is December, with an average hourly wind speed of 8.9 miles per hour. The calmer time of year lasts for 5.6 months, from May 5 to October 23. The calmest month of the year in Viana do Castelo is September, with an average hourly wind speed of 6.8 miles per hour.
The predominant average hourly wind direction in Viana do Castelo varies throughout the year. The wind is most often from the north for 8.5 months, from January 31 to October 14 and for 2.4 weeks, from November 9 to November 26, with a peak percentage of 59% on July 23. The wind is most often from the south for 3.7 weeks, from October 14 to November 9 and for 1.5 months, from December 16 to January 31, with a peak percentage of 33% on October 28. The wind is most often from the east for 2.9 weeks, from November 26 to December 16, with a peak percentage of 30% on December 9. Water TemperatureViana do Castelo is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water. The average water temperature experiences some seasonal variation over the course of the year. The time of year with warmer water lasts for 4.2 months, from June 17 to October 24, with an average temperature above 62°F. The month of the year in Viana do Castelo with the warmest water is August, with an average temperature of 64°F. The time of year with cooler water lasts for 3.5 months, from December 31 to April 16, with an average temperature below 57°F. The month of the year in Viana do Castelo with the coolest water is February, with an average temperature of 56°F.
Best Time of Year to VisitTo characterize how pleasant the weather is in Viana do Castelo throughout the year, we compute two travel scores. The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Viana do Castelo for general outdoor tourist activities is from mid June to early September, with a peak score in the third week of July. Tourism Score in Viana do CasteloThe beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Viana do Castelo for hot-weather activities is from mid July to late August, with a peak score in the last week of July. Beach/Pool Score in Viana do CasteloMethodologyFor each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed. Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies. Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more. Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter. Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter. Growing SeasonDefinitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere). Temperatures in Viana do Castelo are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year. Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F. Solar EnergyThis section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation. The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year. The brighter period of the year lasts for 3.1 months, from May 15 to August 20, with an average daily incident shortwave energy per square meter above 6.6 kWh. The brightest month of the year in Viana do Castelo is July, with an average of 7.7 kWh. The darker period of the year lasts for 3.7 months, from October 24 to February 15, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest month of the year in Viana do Castelo is December, with an average of 1.6 kWh.
TopographyFor the purposes of this report, the geographical coordinates of Viana do Castelo are 41.693 deg latitude, -8.833 deg longitude, and 39 ft elevation. The topography within 2 miles of Viana do Castelo contains very significant variations in elevation, with a maximum elevation change of 955 feet and an average elevation above sea level of 96 feet. Within 10 miles contains very significant variations in elevation (2,569 feet). Within 50 miles contains large variations in elevation (5,026 feet). The area within 2 miles of Viana do Castelo is covered by water (39%), artificial surfaces (32%), and trees (22%), within 10 miles by water (48%) and trees (23%), and within 50 miles by water (53%) and trees (19%). Data SourcesThis report illustrates the typical weather in Viana do Castelo, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016. Temperature and Dew PointThere are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Viana do Castelo. For each station, the records are corrected for the elevation difference between that station and Viana do Castelo according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations. The estimated value at Viana do Castelo is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Viana do Castelo and a given station. The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Viana do Castelo and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data. Other DataAll data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus. All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid. Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations. Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory. Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database . Time zones for airports and weather stations are provided by AskGeo.com . Maps are © OpenStreetMap contributors. DisclaimerThe information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site. We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands. We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader. Please review our full terms contained on our Terms of Service page. |