Bilbao, where it lies in the map

Bilbao, the largest city in the Basque Country, is located on the northern Spanish coast, where the climate is different from the rest of Spain, in fact, it is temperate oceanic, with mild, rainy winters and quite cool to pleasantly warm summers.
Here are the average temperatures.
Bilbao - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)556710131515131186
Max (°C)131516172023252624211614
Min (°F)414143455055595955524643
Max (°F)555961636873777975706157

Precipitation is quite abundant, in fact, it amounts to 1,200 millimeters (47 inches) per year, and it's frequent from October to May, while from June to September, when it rains on average from seven to nine days per month, it becomes a bit less frequent. Here is the average precipitation.
Bilbao - Average precipitation
MonthJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec.(mm)125959512590656080751201401151185
Prec.(in)4.93.73.74.93.52.62.43.134.75.54.546.7
Days13111113128789111212127

In addition, the wind blows frequently from the ocean, and can be strong, especially in the cold half of the year. On the other hand, the warm and dry southerly wind, which descends from the Cantabrian Mountains, can cause sudden increases in temperature due to the foehn effect.
At night, fog can form, especially in autumn, and a little less frequently in spring.

Winter, from December to February, is mild and rainy. The average temperature in January is 9 °C (48 °F). Atlantic disturbances regularly pass over northern Spain, bringing rain and cloudy skies.
Cold spells are quite rare, and don't produce remarkable effects. However, there may be some cold days, with highs around 5 °C (41 °F). Snow is a rare phenomenon, though not impossible. At night, slight frosts can occur, typically 1-2 degrees Celsius below freezing (0 °C or 32 °F), although the temperature dropped to -7 °C (19 °F) in January 1985 and to -4 °C (25 °F) in February 2012.

Spring, from March to May, is cool, cloudy and rainy. Wind and humidity can increase the feeling of cold. When the wind blows from the south, there may be sudden increases in temperature, with the first warm periods, maybe only for a day or two.

In Summer, from June to August, generally, the days are pleasantly warm, while nights are cool. Some Atlantic disturbances, which can bring rainy and cool weather, with highs around 20 °C (68 °F), can affect this area even in summer, although more rarely than in the other seasons, in fact, there may be entire weeks without rain, even though it depends on the year. Hot days are rare: the temperature exceeds 30 °C (86 °F) for a few days per month, and even in these cases, the nights remain cool. Every so often, scorching days can occur, with highs near 40 °C (104 °F), due to the aforementioned down-slope wind from the south, but even in these cases, the temperature at night usually drops below 20 °C (68 °F). In addition, these are usually isolated events, as happened on July 31, 2013, when the temperature reached 42 °C (108 °F) for one day. Only in August 2003, which, in a way, it does not count because it was an exceptional summer in all of Western Europe, there have been several hot days in a row, and the temperature reached as high as 46 °C (115 °F).

Autumn, from September to November, is cool and rainy, especially in October and November, while in September, the temperature is still pleasant and the rains are not so frequent, so much so that there is no big difference with the summer, especially in the first half of the month. In autumn, on clear nights, fog can form.

Bilbao

Bilbao does not get a lot of sun, since cloudy skies are predominant, especially in the long period when Atlantic depressions are frequent, ie from October to May. Here are the average sunshine hours per day.
Bilbao - Sunshine
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Hours334556665433

The sea near Bilbao is very cool, if not a bit cold, even in midsummer, since the water temperature reaches at most 20/21 °C (68/70 °F) from July to September.
Bilbao - Sea temperature
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Temp (°C)131212131518202120181513
Temp (°F)555454555964687068645955

Best Time


The best time to visit Bilbao is from June to mid-September, since it is the warmest and driest period of the year. It's better to bring a sweatshirt and a light jacket for the evening and for rainy days; an umbrella can be useful too.

Back to the Basque Country.