Climate and monthly weather forecast
Viana do Castelo, Portugal

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The climate of Viana do Castelo

Viana do Castelo, located in Portugal, possesses a warm summer Mediterranean climate, also known as a Csb climate according to the Köppen climate classification. The general atmospheric conditions span across a spectrum marked by hot summers accompanied by cooler evenings and moderate to wet winters.

The annual temperature registers a low of 4.9°C (40.8°F) in the coldest month rising to a peak of 26.4°C (79.5°F) during the summertime. It's interesting to note that sea temperature varies from 13.8°C (56.8°F) to 18.3°C (64.9°F), indicating conducive conditions for sea-related activities for the most part of the year. Daylight hours are shortest in December at 9.2 hours, extending up to a generous 15.2 hours during summer, allowing ample time for sightseeing and outdoor activities.

Unusual patterns manifest in the form of the maximum temperature of 26.4°C (79.5°F) occurring not in the traditionally hottest July but in August. Conditions seem to remain somewhat constant during the colder months, with the lowest mercury level recorded in January, only to rise slightly in February and March, instead of a more sharp upward trajectory.

The best time to visit Viana do Castelo

The favourable period to enjoy the scenic beauty and cultural ambiance of Viana do Castelo falls between May and September. During these months, temperatures hover between 20.7°C (69.3°F) and 26.4°C (79.5°F), providing a comfortable warm climate ideal for outdoor activities. The daylight hours range from 14.5 to 15.2 hours, making it an excellent time for sightseeing and exploration. Sea temperatures also stay relatively warm, from 16.3°C (61.3°F) to 18.3°C (64.9°F), encouraging maritime pursuits and beach activities.

The worst time to visit Viana do Castelo

Winter months, from December through to February, stand as the least attractive for visits owing to lower temperatures that dip to 4.9°C (40.8°F) along with reduced daylight hours. This period sees the shortest daylight stretches, dropping to an annual minimum of 9.2 hours in December. Sea temperatures also lose their warmth, falling to 13.8°C (56.8°F), discouraging sea swimming and water sports activities.

Spring weather in Viana do Castelo

Spring in Viana do Castelo ushers in a temperate era from March to May, with temperatures improving from a gentle 17.9°C (64.2°F) to a warmer 20.7°C (69.3°F). Correspondingly, daylight hours increase from 12 hours in March up to 14.5 hours by May. Sea temperatures moderately rise from 13.8°C (56.8°F) to 16.3°C (61.3°F), initiating the start of the nautical season.

Summer weather in Viana do Castelo

June to August constitute the summer period when an influx of tourists seek out the warmth and beauty of Viana do Castelo. Temperatures briskly rise from a comfortable 24.5°C (76.1°F) to a balmy 26.4°C (79.5°F). The daylight amply supports summer activities, averaging between 14.9 and 15.2 hours. Sea temperatures hover between 17.2°C (63°F) and 17.9°C (64.2°F), making it an excellent period for beach and water activities.

Autumn weather in Viana do Castelo

Autumn, stretching from September to November, presents a gradually cooling course with temperatures lowering from 24.8°C (76.6°F) down to 17.4°C (63.3°F). Daylight hours gradually decrease from 12.5 hours to 9.9 hours. Yet, with sea temperatures maintaining their warmth between 18.3°C (64.9°F) and 16.9°C (62.4°F), it remains a pleasant time for water sports enthusiasts.

Winter weather in Viana do Castelo

Winter, from December to February, registers the coldest weather conditions of the year. The temperatures fall to the year’s minimum, reaching 4.9°C (40.8°F). Daylight recedes to as low as 9.2 hours per day, contributing to the cold, less inviting weather. Sea temperatures also plummet to their lowest - dropping from 15.4°C (59.7°F) in December to 13.8°C (56.8°F) in February, dampening the prospects for swimming or boating activities.

Weather in January

For the region of Viana do Castelo, Portugal, the beginning of the year embodies moderate weather conditions. January experiences average high temperatures of 14.6°C (58.3°F) and low temperatures descend to an average of 4.9°C (40.8°F). Weather in January »

Weather in February

Warmer rays of sunlight begin to seep into the atmosphere of Viana do Castelo as February edges on, offering a more comfortable weather spectrum than the previous month of January. With a sea temperature averaging 13.8°C (56.8°F), an occasional mild breeze from the coast may waft into town. Weather in February »

Weather in March

The weather in Viana do Castelo during March balances itself between the chilling remnants of winter and the blooming warmth of spring. The high temperature averages around 17.9°C (64.2°F) marking a progress in warmth from the preceding month of February. Weather in March »

Weather in April

April's weather reflects the full arrival of spring in Viana do Castelo. The month expresses a higher average temperature of 18.5°C (65.3°F). Each day has longer sunlight hours than March and this illumination brings life to the blooming flora of the city. Weather in April »

Weather in May

In May, the weather in Viana do Castelo is characterized by substantial daylight and increasing heat. With the high temperature reaching an average of 20.7°C (69.3°F), the overall atmosphere becomes more summery than that of April. Weather in May »

Weather in June

June in Viana do Castelo welcomes summer with an average temperature plunge of 24.5°C (76.1°F). The days are elongated the most during this month relative to any other month in the year. Holiday-goers flock to the city due to the pleasant weather conditions, which are preferable compared to the increasing temperature of July. Weather in June »

Weather in July

July in Viana do Castelo carries the heat of summer to its peak with an average high of 26.3°C (79.3°F). From being an extremely bright and long day in June, the day length subtly recedes in July. Balmy weather and calmer sea breezes mark a distinction from the expected weather in August. Weather in July »

Weather in August

August conveys the tail end of summer in Viana do Castelo, Portugal. With the highest low temperature of the year at 15.1°C (59.2°F), it enjoys a tiny marginally cooler climate compared to July. Owing to the generally pleasant weather, activities in Viana do Castelo rarely face any hindrance. Weather in August »

Weather in September

September brings the commencement of autumn to Viana do Castelo. Contrasting with the warmer temperature in August, the average high temperature declines to 24.8°C (76.6°F). The length of daylight noticeably shortens, sympathizing with the midnight blues of winter. Weather in September »

Weather in October

October in Viana do Castelo is marked by a significant decrease in temperature and daylight from the previous month. It is substantially chillier with a low average temperature of 11.2°C (52.2°F), but not as cold as November. Weather in October »

Weather in November

November is distinctly cooler in Viana do Castelo than the preceding months, a transition that is quite evident following October. A further decrease in temperature can be expected with the high averaging 17.4°C (63.3°F), portending the severity of winter that December brings. Weather in November »

Weather in December

The weather in December in Viana do Castelo, Portugal, is distinguished by its winter characteristic. Temperature highs averaging 15.2°C (59.4°F) indicate the oncoming chill of the winter season. It has fewer daylight hours than the month of November, bringing early twilight and a crisp climate. Weather in December »

Frequently asked questions

What are the coldest months in Viana do Castelo?

Viana do Castelo's temperature records reveal January as the coldest month, marked by average highs of 14.6°C (58.3°F) and lows of 4.9°C (40.8°F).

When is the sea coldest in Viana do Castelo?

The months with the coldest seawater in Viana do Castelo, Portugal, are February and March, with an average sea temperature of 13.8°C (56.8°F).

When are the longest days in Viana do Castelo?

The month with the longest days is June, with an average of 15h and 12min of daylight.

What is the hottest time of year in Viana do Castelo?

Temperature readings in Viana do Castelo, Portugal, reach their annual highs in August, averaging 26.4°C (79.5°F) and a minimum average of 15.1°C (59.2°F).

What is the month with the warmest sea water in Viana do Castelo?

With an average sea temperature of 18.3°C (64.9°F), September is the month with the warmest seawater.

When is Daylight Saving Time (DST) in Viana do Castelo?

On Sunday, 27. October 2024, at 02:00, Daylight Saving Time ends in Viana do Castelo, Portugal, and the time zone changes from WEST to WET. The next Daylight Saving Time starts on Sunday, 30. March 2025, at 01:00, and the time zone reverts from WET to WEST.

What is the month with the shortest days in Viana do Castelo?

The month with the shortest days in Viana do Castelo, Portugal, is December, with an average of 9h and 12min of daylight.

Average temperature
Viana do Castelo, Portugal

Average temperature - Viana do Castelo, Portugal

The warmest month (with the highest average high temperature) is August (26.4°C).
The month with the lowest average high temperature is January (14.6°C).

The month with the highest average low temperature is July (15.3°C).
The coldest month (with the lowest average low temperature) is January (4.9°C).

Average sea temperature
Viana do Castelo, Portugal

Average sea temperature - Viana do Castelo, Portugal

The best month for swimming (with the highest average sea temperature) is September (18.3°C).
The coldest months (with the lowest average sea temperature) are February and March (13.8°C).

Average daylight
Viana do Castelo, Portugal

Average daylight - Viana do Castelo, Portugal

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).

Viana do Castelo, Portugal

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