Three weeks after Katrina, the SSTs south of LA are still several degrees cooler (as they are further down in the GOM as well):

http://marine.rutgers.edu/mrs/sat_data/?product=sst&region=gulfmexico&nothumbs=0

You'll have to change the date range and refresh once you link.

EDIT - OK now Rita is entering the area with the warmest SSTs over the next 12 hours. If she doesn't get her act tog tonight/tomorrow morning I don't see how conditions are going to be more favorable in a day or so, between the keys and say east of 89W. Water temps are not cool, but not as warm, in that area, and isn't there more shear near the keys? Will this shear still be in place 24 hrs from now? I think once she reaches south of the keys, intensity will not increase until she gets further west. SSTs don't increase until 90W but I am thinking the loop current is a little further east than that, but have no idea if that is still a factor, after Katrina.

Does appear that cloud tops are starting to get a little cooler on the wv loop, so the anticipated increase to hurricane strength will be coming, we will start to see the pressure drop with the next recon and throughout the evng.