During winter time, i.e. from 1 a.m. on the last Sunday in October to 1 a.m. on the last Sunday in March, the official time in mainland Portugal and Madeira is the Universal Time Coordinated (UTC).

The rest of the year (between 1 a.m. on the last Sunday in March and 1 a.m. on the last Sunday in October), summer time is in effect and the official time in mainland Portugal and Madeira is Universal Time Coordinated plus one hour.

In the Azores, the time is one hour earlier than in the rest of Portugal and therefore one hour earlier than the Universal Time Coordinated during winter time and two hours earlier during summer time.