Afraid I'm going to be a voice of dissention here. Forget the weather forecast. My dad has designed numerous radar systems, including weather radar. According to him, weather forecasters can't do anymore than look at what is going on now and try to predict what those systems can and will do. There are so many variables--weather really isn't predictable. According to my dad, you can generally trust a 24 hour,maybe a 48 hour forecast, but that's it.
My advice--for what it's worth--is this. Look at the forecast if you want to, sure. But, be sure to look at the average highs and lows--as well as the extemes. Chances are, the weather will be similar to the average, but there is always the possiblity of the extremes.
Traveling to Florida around now? I would plan on mostly 70s by day and 50s by night. It's dry season, so rain shouldn't be a factor. I would however, throw in a pair of shorts. It can get hot and 90 degrees in jeans is no fun. It can also be really cold--especially mornings and evenings. Throw in a couple of items you can layer. I always want gloves if I'm cold. 40s is cold if you've only packed for 70s! I know it sounds like I'm advocating bringing a steamer trunk. You probably won't use your "extreme-wear," but it's only a couple of extra pieces and if you need it, you'll be so happy brought it.
Enjoy!!