Portugal has a mixture of religious and state public holidays during the year. On these days you may find some tourist attractions and shops closed, especially Christmas, Easter and on 1st January. Banks, post offices and public offices will be closed.

Note that holidays occurring on a Saturday or Sunday are NOT moved. 

Trains and buses do operate, usually to Sunday/Holiday times but with alterations especially for the Easter and Christmas/New Year Holidays.  

Here's the list:

1 Jan New Year's Day.

14-16 Apr Easter. NB Easter Monday is NOT a holiday in Portugal

25 Apr Freedom Day. 
1 May Labour Day. 
10 Jun Portugal Day.
15 Jun Corpus Christi
8 Dec Immaculate Conception. 
25 Dec Christmas Day
15 Aug Assumption. 

5 Oct Republic Implantation

1 Nov All Saints Day

1 Dec Restoration of Independence