Bilbao and its metropolitan area have an oceanic climate with mild winters and warm summers. The climate of Bilbao and the rest of the north-western part of Spain (the so-called Green Spain) is different from the rest of the country.

Said proximity to the ocean also makes that the two most defined seasons (summer and winter) remain mild, with low intensity thermal oscillations. Its average annual temperature is 19.1 °C during the day and 9.4 °C at night. In the coldest month – January, typically the temperature is around 13-14 °C during the day and 5 °C at night. In the warmest month – August, the typically temperature is around 25-26 °C during the day and about 15 °C at night.

Bilbao has on average 128 precipitation days a year, therein average few to dozen rainy days per month (≥ 1 mm), ranging from 7 in July to 13 in January. The average annual precipitation is 1195 mm, ranging from 62 mm in July to 141 mm in November. This is one of the highest results in Spain, like the rest of Green Spain and Bay of Biscay area. Precipitation in the region is abundant, and given the latitude and atmospheric dynamics, rainy days represent 45% and cloudy days 40% of the annual total.