First thing you have to do is examine exactly where the rainfall in SFL has been above average. The map on this link is good for viewing rainfall totals:
http://www.sfwmd.gov/curre/rainmaps/monthly.html
Only three of the counties on this map experienced above average rainfall during May. The rest of them had below average rainfall. Moreover, the "district average" was .68 inches below normal for the month. Sure, a few counties clocked in with decently above average totals, but overall I'd call May slightly below average for South Florida.

Another important point to make is the timing of the rainfall. The past few days have been pretty rainy for much of the Florida Peninsula, right? In fact, we had some decent batches of rain come across the peninsula late last night. Now, does the May rainfall/Florida hurricanes relationship some kind of switch that automatically goes off 12 AM on 1 June? With so much rainfall occuring so late in the month, I'd be weary of just how much these late totals really count.

And then there's the argument that you can't really predict Florida (or US) landfalls several months in advance. Dr. Gray has been one of the foremost experts to state that landfall predictions months in advance simply cannot be made (with accuracy) at this time. This is the stance that I tend to agree with. Since the advent of the 3 day forecast track, hurricane forecasters have at one time or another experienced problems in producing accurate forecasts. Three months in advance? Forget about it. It simply is not possible to predict the small variations that can occur in the atmosphere months in advance. Sure, the Bermuda High might be weaker than average for the majority of the summer, but if the position and strength are right for just ONE storm, disaster can occur.

This argument has come up before, but it is one worth recalling from time to time.