 Daylight saving time (locally known as "Hora de Verão", meaning 'summer time') is observed nationwide from the last Sunday in March to the last Sunday in October, so that every year, continental Portugal and Madeira temporarily use , and the Azores temporarily use .In the early 19th century, Portugal adopted mean solar time.Navy (located in Lisbon) and Coimbra Astronomical Observatories calculated solar time to be used as legal time in their longitude regions.