We have done a lot of day trips and always check the weather and never book until a couple of days before we leave. We have also stayed over and pre-booked the ferry and the hotel. If you pre book and you are going in the Summer months then it is unlikely the weather will be bad. Of course, if you go later in the season and stay over, which we would not do, you could get bad weather.
Davy is talking about day trips late in the season, not going and staying over.
Marina, I would assume that talking about rough weather and taking a bucket many be a joke, but it also may put of anyone who as never been.