Two easier seasons for the cities, five airports, the euro, two clocks, and Spanish as the official language with others beside it in their regions.
Best season
April and May, then September and October
Madrid has frost from December to February, and 40.7°C was recorded at the Retiro on 14 August 2021. Seville’s summer is long, hot and dry. Barcelona’s rain is heaviest in autumn and spring. Bilbao is wet from October to April. Tenerife’s coasts stay mild in winter and warm in summer.Madrid · WikipediaSeville · WikipediaBarcelona · WikipediaBilbao · WikipediaTenerife · Wikipedia
Main airports
Madrid, Barcelona, Tenerife South, Seville and BilbaoMAD · BCN · TFS · SVQ · BIO
Central European Time on the mainland, Western European Time in the CanariesUTC+1 · UTC+0
Daylight saving runs from the last Sunday in March to the last Sunday in October: the mainland moves to UTC+2, the Canaries to UTC+1.Time in Spain · Wikipedia
Official language
Spanish
Castilian is the language of the state. Basque, Catalan, Galician and Aranese are co-official in their regions. In the Valencian Community the official name of Catalan is Valencian.Spain · Wikipedia