In the past few years, the refurbishment schedule has been that Blizzard closed 1st from November to mid to late December, then Typhoon closed until the end of February, so it will depend on when you are there.
Personally, after about November I take a hiatus from the waterparks until about March. For me it is too cold if the temps dip much below 82 degrees... but I have always had "thin blood", so I fit right in here if Florida! For those from Europe or further north, the waterparks will likely be "just right"!