First of all any weather forecast more than 3 days out is pure speculation...they have little to no idea what the weather will actually be a week from today, and any meteorologist worth his or her salt will admit that.
Secondly, we were in Florida and Discovery Cove last week and the weather changes drastically from hour to hour. It would be literally pouring down rain (hot rain) at one time and half an hour later, bright blazing sun. And vice versa. I wouldn't worry about it.