Oeiras Climate & Monthly Temperature Overview – Portugal

Summer in Oeiras

Summer in Oeiras is warm and sunny, with average temperatures ranging from 20°C to 26°C (68°F to 79°F). July and August are the warmest months, with average temperatures peaking at 26°C (79°F). The humidity is relatively low, making it pleasant to spend time outdoors. Rainfall is infrequent during this season, with only occasional showers or thunderstorms. Oeiras boasts beautiful beaches, such as Praia de Santo Amaro de Oeiras, where visitors can enjoy swimming, sunbathing, and other water activities. The area also offers opportunities for golf, cycling, and hiking.

Winter in Oeiras

Winter in Oeiras is mild and rainy, with average temperatures ranging from 10°C to 15°C (50°F to 59°F). December and January are the coldest months, with average temperatures dropping to 10°C (50°F). The humidity is higher than in summer, and rainfall is more frequent, with drizzle or showers occurring on average of 7-10 days per month. Despite the rain, Oeiras has plenty of indoor attractions to offer, including museums, shopping malls, and theaters. The city is also home to several historical landmarks, such as the Torre de São Julião da Barra, a 16th-century fortress that offers stunning views of the Tagus River.

Monthly Average Temperatures

Oeiras, Portugal, enjoys a Mediterranean climate characterized by warm, dry summers and mild, wet winters. The average temperature throughout the year is a pleasant 16.4°C (61.5°F). During the summer months (June to September), temperatures reach an average high of 27°C (80.6°F) and an average low of 17°C (62.6°F). While winter temperatures tend to be milder, it can get chilly at night, with average lows dropping to 7°C (44.6°F). The warmest month in Oeiras is August, with an average temperature of 23.5°C (74.3°F), while the coldest month is January, with an average temperature of 11.1°C (52°F).

Rainfall and Sunshine

Oeiras receives an average annual rainfall of 660 mm (26 in), which is spread fairly evenly throughout the year. The wettest months are November and December, when rainfall can reach up to 100 mm (4 in) per month. In contrast, the driest months are July and August, when precipitation is typically less than 10 mm (0.4 in) per month. Oeiras also enjoys plenty of sunshine, with an average of around 2,800 hours per year. The sunniest months are June and July, with an average of over 10 hours of sunshine per day. However, even during the winter months, Oeiras still receives an average of around 5 hours of sunshine per day.

Types of Clouds in Oeiras, Portugal

Oeiras, Portugal, experiences a range of cloud types due to its coastal location and temperate climate. Cumulus clouds, characterized by their puffiness and resemblance to cotton balls, are common in the summer months. These clouds often indicate fair weather but can grow into larger formations and produce rain. Cirrus clouds, thin, wispy clouds that resemble hair or feathers, are also prevalent in Oeiras. These clouds are typically composed of ice crystals and indicate high-altitude weather conditions. Stratus clouds, which appear as a continuous gray layer, are common during the winter months and often bring overcast skies and precipitation.

Cloud Patterns and Weather Conditions

The patterns and formations of clouds in Oeiras can provide insights into the weather conditions. When cumulus clouds develop into cumulonimbus clouds, they can indicate the potential for thunderstorms or heavy rain. Breaks in the stratus cloud cover often reveal patches of blue sky, suggesting the possibility of clearing weather. Conversely, increasing cloud cover, particularly in the form of cirrostratus or altostratus clouds, can indicate approaching precipitation. Observing cloud patterns and formations can be a valuable tool for understanding the current and upcoming weather conditions in Oeiras.

Monthly Precipitation

In Oeiras, the wettest month is December with an average precipitation of 137 mm. January and November follow closely with 122 mm and 115 mm respectively. The driest month is July with just 3 mm of precipitation. This indicates a clear seasonal pattern of precipitation, with much more rainfall during the winter months and very little during the summer months.

Annual Precipitation

The average annual precipitation in Oeiras is 725 mm, which is relatively low compared to other regions of Portugal. This is likely due to its location on the coast, which means that it is exposed to the moderating effects of the Atlantic Ocean. As a result, Oeiras experiences a more Mediterranean climate than other parts of the country, with warm, dry summers and mild, wet winters.

Rainfall Patterns

Oeiras, Portugal, experiences a Mediterranean climate with distinct wet and dry seasons. During the winter months (October to March), the region receives a significant amount of rainfall, with an average of 6 to 7 inches per month. The heaviest rainfall typically occurs during the months of November and December. During the summer months (May to September), rainfall is scarce, with an average of less than 1 inch per month. August is often the driest month, with some years receiving no rainfall at all.

Seasonal Variations

The seasonal variations in rainfall are driven by the North Atlantic Oscillation (NAO), a weather pattern that influences the movement of storms across the North Atlantic. During positive NAO phases, storms are more likely to track southward and bring wet weather to Oeiras. Conversely, negative NAO phases lead to drier conditions. The NAO index is particularly influential during winter, when it can account for up to 40% of the rainfall variability in Oeiras. During strong negative NAO events, such as the one observed in the winter of 2017-2018, Oeiras can experience extended periods of drought-like conditions.

Occurrence of Snowfall in Oeiras, Portugal

Snowfall is an uncommon occurrence in Oeiras, Portugal, a municipality located on the outskirts of Lisbon. The region generally experiences a mild climate due to its proximity to the Atlantic Ocean, which moderates temperatures year-round. However, on rare occasions, cold weather fronts from the north or east can bring snowfall to the area. The most recent snowfall event occurred in 2005, when several centimeters of snow accumulated on the ground.

Effects of Snowfall in Oeiras

Snowfall in Oeiras can have significant impacts on the municipality and its residents. Due to the infrequent nature of the event, infrastructure and emergency services may not be fully prepared for the challenges posed by snow and ice. Transportation can be disrupted, with roads becoming impassable and public transportation services experiencing delays or cancellations. Additionally, snowfall can lead to power outages and communication difficulties. Residents are advised to stay indoors and avoid unnecessary travel during heavy snowfall. Municipal authorities typically prioritize snow removal and gritting operations on main roads and access points to ensure the safety and well-being of the community.

Sun Exposure and Health Benefits in Oeiras, Portugal

Oeiras, Portugal, enjoys ample sunshine throughout the year, with an average of over 2,800 hours of sunshine annually. This exposure to sunlight provides numerous health benefits, including the synthesis of vitamin D in the skin. Vitamin D plays a crucial role in calcium absorption, bone health, and immune function. Adequate sunlight exposure can also improve mood, boost energy levels, and reduce the risk of certain chronic diseases, such as osteoporosis and certain types of cancer.

Precautions for Sun Exposure in Oeiras, Portugal

While sunlight is beneficial in moderation, excessive exposure can lead to harmful effects such as sunburn, skin cancer, and premature aging. In Oeiras, it is essential to take precautions to protect oneself from the sun’s harmful rays. These measures include wearing protective clothing, using sunscreen with a high SPF, seeking shade during peak hours of sunlight, and avoiding prolonged exposure to the sun. Additionally, it is advisable to consult with a healthcare professional to determine the optimal amount of sunlight exposure for individual needs. By following these precautions, individuals can enjoy the health benefits of sunlight while minimizing the risks associated with excessive exposure.

Moon’s Appearance and Visibility

In Oeiras, Portugal, the moon’s appearance and visibility vary throughout the month. During the new moon phase, the moon is not visible in the sky as it is located between the Earth and the Sun. As the moon waxes, it becomes increasingly visible in the evening sky, culminating in a full moon phase when it is fully illuminated by the Sun. During this phase, the moon is visible all night long. As the moon wanes, its visibility decreases, and it is eventually no longer visible in the sky during the new moon phase.

Moon’s Influence on Tides

The moon’s gravitational pull has a significant influence on tides in Oeiras. During a full moon and new moon phases, the moon’s gravitational pull combines with that of the Sun, resulting in higher high tides and lower low tides known as spring tides. During quarter moon phases, the moon’s gravitational pull counteracts that of the Sun, resulting in lower high tides and higher low tides known as neap tides. The amplitude of tides in Oeiras varies throughout the year due to changes in the moon’s distance from the Earth and the Earth’s tilt relative to the moon.

Seasonal Variations

The humidity levels in Oeiras, Portugal, exhibit distinct seasonal variations throughout the year. During the summer months (June to September), humidity tends to be relatively low, with average relative humidity values ranging between 50% and 65%. The warm, dry air masses from the Atlantic Ocean contribute to these conditions. In contrast, winter months (December to March) bring higher humidity, with average relative humidity levels typically between 75% and 85%. The cooler temperatures and increased precipitation create a more humid atmosphere.

Daily Fluctuations

In addition to seasonal variations, humidity in Oeiras also exhibits diurnal fluctuations. Generally, humidity levels are lowest during the warmest part of the day, typically between noon and 4 pm. As the sun sets and temperatures cool, humidity tends to increase, reaching its peak values around sunrise. This variation is influenced by the diurnal cycle of evaporation and condensation processes, with higher evaporation rates during the day leading to lower humidity levels.

Wind Speed and Direction

Oeiras, Portugal, experiences moderate year-round wind speeds that vary depending on the season. The warmest months, June through September, have average wind speeds ranging from 14 to 17 kilometers per hour (8.7 to 10.6 miles per hour), with prevailing winds blowing from the southwest. During the cooler months, October through May, wind speeds increase slightly to an average of 17-19 kilometers per hour (10.6-11.8 miles per hour), with winds predominantly blowing from the northwest.

Wind Impact

The prevailing wind patterns in Oeiras have a significant impact on local weather and climate. The southwesterly winds during the summer bring warm, humid air from the Atlantic Ocean, contributing to the mild temperatures and comfortable humidity levels. In contrast, the northwesterly winds during the winter months bring colder, drier air from mainland Portugal, resulting in occasional cold spells and increased cloud cover. The strong and consistent winds also create favorable conditions for windsurfing and kitesurfing, making Oeiras a popular destination for these water sports.

Best Time to Visit Oeiras for Weather

The best time to visit Oeiras for favorable weather is during the shoulder seasons, namely May-June and September-October. During these months, temperatures range from a comfortable 19-24°C (66-75°F), providing ample opportunities for outdoor activities without the oppressive heat or excessive crowds of summer.

Best Time to Visit Oeiras for Events and Festivals

Oeiras hosts several lively events and festivals throughout the year, making it an excellent destination for cultural immersion. The Oeiras Jazz Festival, held in May, features an electrifying lineup of national and international jazz performers. The Santo Amaro Festival, taking place in June, honors the patron saint of Oeiras with traditional processions and lively entertainment. For those seeking art and culture, the Oeiras Film Festival in October showcases a diverse selection of international films, workshops, and Q&A sessions with renowned filmmakers.

Solar Energy Potential

Oeiras, Portugal boasts exceptional solar energy potential due to its favorable geographical location and abundant sunshine. The city receives an average of over 3,000 sunshine hours annually, providing an ideal setting for harnessing solar energy. This high solar insolation creates significant opportunities for the development and deployment of solar energy technologies, such as photovoltaic (PV) systems and solar thermal collectors.

Solar Energy Initiatives

Recognizing the potential of solar energy, Oeiras has implemented several initiatives to promote its development. The city has established a goal of generating 100% of its electricity from renewable sources by 2030, with solar energy playing a crucial role. To achieve this target, Oeiras has implemented a range of incentives, including subsidies for solar energy installations, tax breaks, and streamlined permitting processes. Furthermore, the city has developed educational programs to raise awareness about the benefits of solar energy among its residents and businesses. These combined efforts have led to a surge in solar energy installations, with numerous residential and commercial buildings adopting solar panels and thermal systems to meet their energy needs.

Coastal Plains and Bluffs

Oeiras is situated along the Atlantic coastline, showcasing a diverse topography characterized by coastal plains and bluffs. The westernmost area of the municipality, bordering the ocean, features a strip of flat coastal plains extending inland for several kilometers. These plains are dotted with pristine beaches, inviting both locals and tourists to bask in the warm sunshine and enjoy the refreshing ocean breeze. As one moves further inland, the landscape gradually transitions into a series of low-lying bluffs overlooking the coastal plains. These bluffs offer panoramic views of the Atlantic Ocean, providing breathtaking vistas for residents and visitors alike.

Inland Valleys and Ridges

Beyond the coastal plains and bluffs, the topography of Oeiras becomes more rugged and diverse. The northern and central regions of the municipality are dominated by a network of valleys and ridges. The valleys, often carved by ancient rivers and streams, provide a verdant tapestry of agricultural land, vineyards, and lush greenery. The ridges, which rise to moderate elevations, offer scenic hiking trails and mountain biking paths, allowing outdoor enthusiasts to explore the area’s natural beauty. The highest point in Oeiras is located in the Serra de Carnaxide, a small mountain range that forms the northern boundary of the municipality. From the summit, one can enjoy breathtaking panoramic views of the surrounding countryside, the Lisbon metropolitan area, and the Atlantic Ocean.

Lisbon Humberto Delgado Airport (LIS)

Lisbon Humberto Delgado Airport (LIS), also known as Portela Airport, is the nearest airport to Oeiras, Portugal. It is located about 12 kilometers (7 miles) from the city center of Oeiras and is easily accessible by car, taxi, or public transportation. The airport serves as the main gateway to Portugal and offers a wide range of domestic and international flights. Travelers can connect to major cities across Europe, as well as other destinations in North America, Africa, and Asia. The airport features a modern terminal with various amenities, including duty-free shops, restaurants, and currency exchange services.

Cascais Municipal Aerodrome (CAJ)

Cascais Municipal Aerodrome (CAJ), also known as Tires Airport, is another nearby airport located approximately 15 kilometers (9 miles) from Oeiras. It primarily serves private and charter flights and is not as large or busy as Lisbon Humberto Delgado Airport. However, it offers a more convenient option for travelers who prefer to avoid the crowds and have access to a smaller and quieter airport. Cascais Municipal Aerodrome is easily accessible by car or taxi and provides limited public transportation options. It is suitable for travelers looking for a more exclusive and personalized travel experience.

Historical Significance

Oeiras holds a place of historical importance in Portuguese history. It was a royal estate during the 15th and 16th centuries, and the Portuguese royal family often resided here. The Palace of the Marquês de Pombal, built in the 18th century, is a testament to the town’s past grandeur. The palace now houses the Center of Marine Sciences and the Oeiras National Museum. Additionally, the Forte de São Julião da Barra, a 16th-century fortress, guards the entrance to the Tagus River, showcasing the town’s strategic military role.

Modern-Day Oeiras

Modern Oeiras is a vibrant and affluent town with a diverse population. It is a hub for technology and innovation, hosting several leading tech companies and research institutions. The town’s proximity to Lisbon, the capital city, makes it an attractive destination for commuters and professionals. Oeiras also boasts a beautiful coastline along the Tagus River, with scenic beaches and stunning views. Its extensive parks, cultural centers, and sports facilities contribute to the town’s high quality of life.