Understanding Spanish Weather: Temperature, Winds, Humidity & More

Weather Elements in Spain

1 – Temperatures

Temperature measures the degree of heat in the air, measured in degrees by a thermometer. Lines connecting points with the same average temperature are called isotherms. Key temperature factors include:

• Latitude: Higher average temperatures are reached in southern latitudes (Andalusia and the Canary Islands).
• Sea Influence: The sea moderates temperatures.
• Altitude: Temperature decreases with altitude, with significant differences between sunny (south-facing) and shaded (north-facing) slopes.

Absolute maximum temperatures (45-47ºC) are reached in the Guadalquivir and Guadiana valleys. In the rest of the peninsula, values range between 35-40ºC, rarely exceeding 30ºC in the north. The annual temperature range is the difference between the coldest and warmest months. January is the coldest month, and July is the warmest. Equatorial regions have intermediate temperatures.

The lowest temperature fluctuations occur in Galicia, and the largest in the Ebro Valley. Absolute minimums occur in the interior Plateau and the Iberian System. Frosts occur when air temperature falls below 0ºC. Coastal areas like Antibes experience fewer frosts due to the sea’s thermoregulatory effect. Advection frost is caused by very cold air masses. Mountain ranges above 2000m experience over 100 frost days annually, while the northern plateau has about 80, and the southern plateau 60-80.

3 – Winds

Winds are caused by temperature and pressure differences between air masses. Wind strength increases with the pressure gradient. Regional winds are classified by origin:

• North and Northeast Winds: Usually cold and dry, originating from cold regions. Examples include the north wind in the Duero basin, Catalonia, and the Balearic and Canary Islands’ trade winds.
• East Winds: Vary by season, hot and dry in summer, mild and humid in spring and autumn. The most important is the Levant in the Mediterranean.
• Southeast Winds: Solano in Murcia, Xaloc in Andalusia, Catalonia, Valencia, and the Balearics.
• South and Southwest Winds: The Abrego (warm and wet) affects the western peninsula, often bringing rain.
• West Winds: Atlantic winds, warm and humid in the west, losing moisture as they cross the plateau.
• Northwest Winds: Cold and dry winds, including the north wind or mistral in the Ebro basin, Galician in the Douro Valley, and the mistral in Catalonia.

4 – Humidity

Solar energy causes water evaporation. Humidity refers to the water vapor content in the atmosphere. It’s usually measured as relative humidity, the percentage of water vapor compared to the maximum saturation level. Humidity is determined by temperature, proximity to water bodies, topography, and vegetation. Highest humidity occurs in coastal regions, decreasing inland except near rivers, reservoirs, or lakes.

5 – Sunshine and Cloudiness

Sunshine measures solar radiation, expressed as the hours of sunlight reaching the ground. Insolation varies throughout the year due to day length and seasons. Landscape also influences sunshine by affecting cloud formation. Andalusia and the southeast have the highest sunshine levels, while the Cantabrian coast and Galicia have the lowest.

Cloudiness measures the percentage of cloudy days per year. Northern Spain has more cloudy days, while Andalusia has more clear days. Cloudiness reduces sunlight but also cools the surface and reflects heat, moderating temperature fluctuations and reducing frost risk. Fogs are common in mountains and river valleys, forming when ground temperature drops below the air’s lower layer temperature. If humidity is sufficient, condensation forms fog. In drier regions, haze or dry fog occurs in summer, consisting of fine dust particles in the air, especially in the Tagus and Guadalquivir valleys.

6 – Evaporation and Aridity

Evaporation depends on sunshine, cloudiness, temperature, humidity, and wind. It’s higher in areas with low clouds, high temperatures, and dry winds, and lower in cloudy, humid, and less windy areas. Aridity is defined by the ratio of evapotranspiration, precipitation, and soil absorption. A territory is arid or dry if precipitation doesn’t compensate for water losses.