It's the same here, it used to be a summer thing but now any halfway decent Sunday in winter, people pour into the place as well. Like Debih says, if you want to go out on a summer Sunday or bank holiday, you go out early and come home late. On Monday, Miss Osc and family went out and were coming home around 6.30ish, she said the queue of cars leaving Howth was 2km long
There is also decent public transport, bus and train, and they would be packed.