Broughty Castle is open all year (except 25th & 26th Dec and 1st, 2nd and 3rd Jan). There are Summer opening hours and Winter opening hours, which are as follows:-
April to September
Monday to Saturday, 10 am to 4 pm
Sunday, 12.30 pm to 4 pm
October to March
Tuesday to Saturday, 10 am to 4 pm
Sunday, 12.30 pm to 4 pm
Closed Monday
For more information visit the website.