this is an old skool problem with all hondas. Under the dash, where the blower motor is, there is a drain tube that lets all the rain water and shit out. It normally gets pinched, or bent from your floor mat hitting it, or just from being put in goofy. If you can straighten it out, it may girgle and clear out. If you pull it off, you may get a ton of water dripping in. So, if it doesn't girgle, pull it off, and blow it out with an air gun. Should work fine after that, and you'll be dry for another 8 years.

It happens a lot with the 4th gens (takes about 6-10 years for all the shit to build up, depending on where you park, like under a tree...)
I've had it happen on every honda I've owned.