Its not bad.Most if not all ride ques are covered or inside.The only time you will get wet is going to the next ride.But in FLA rain does not last allday,normaly A few hours,so it won't be A washout.
The studios side is more indoor rides and shows so you shouldn't have any problems there but IOA has indoor and out door rides and you have to remeber sometimes the rain doesn't last long but have seen people in panchos
Presuming you are going on Saturday of this week (I am as well), Universal in the rain is quite lovely, (as long as it's not all day) everyone decides to leave, clearing the park up. Although, as of late the park's only had ~25,000 people there at a time. So, it hasn't been too bad.
Anyhow, as long as it's a short-shower, it's fine.
Rain turns IOA into a water park. Not as many people like to venture out during the rain, so the park will be less crowded. The shops and restaurants will have more people in them, though, and poncho/umbrella sales increase.
More people will head to USF, since it's mostly indoor attractions. As long as there's no lightning, everything should continue to run as normal.
Adding to Dark Marauder, all the rides are able to run in the rain, with a few exceptions. One being Hulk. If there's a light shower, the other attractions (including outside ones) will most likely be open, but Hulk will probably be closed. The rain messes up the launch system, so they usually wait for the trains to dry (or send them around empty to dry them) after it rains.
So yea, Hulk may be closed in the rain, but that's probably the only one.
I was there in '09 and it rained hard for 30 minutes then off and on. Most people left and we put pancho's on and went to the next ride. We were the only ones walking. It was like everyone was scared of the rain.
We'll be there this weekend and they are calling for rain Saturday between 12-3 pm, but we aren't concerned. It will most likely be a brief shower here and there. I'm hoping the rain and cold weather will keep a lot of people home. ;}
More beads and a better view of the concert for us.