I think it boils down to what you have in your tank. Also, do you have stuff like ATO that is set up. Evaporation will cause some havoc with any tank at this time of the year. Water levels could drop and that could reduce or eliminate the usefulness of your skimmer....as an example.
I agree with Gus...a couple of days is most likely ok...anything longer might require the need to have some top off...and a light feeding. Also, one other thought...do you have your lights on a timer? A day or two with the lights off may be ok....depending on what is in your tank from a coral perspective...more than that...you could have some real problems.