Florida is a warm state with an average of 300 glorious days of sunshine per year, though in summer it can feel humid due to the state's low-lying coastal location.
Summers in Florida can get very hot, as in up to 35°C in the shade, though add on the high humidity and it'll feel 10°C higher than that. The temperatures are lower in the north, although as there's regularly 100% humidity, this is not the most comfortable time to visit.
Between October and May conditions in Florida are generally warm and settled, coinciding with peak season for tourism, particularly in the south. Even in the depths of winter, the lows are only about 10°C, so mild by European standards.
Florida is the thunderstorm capital of the United States. The storms are most likely to occur between May and September, normally in the afternoon, and can last anywhere between a couple of minutes to a couple of hours. In addition hurricane season runs from June to November. If you're unlucky enough to visit when there's a hurricane stay indoors away from windows and doors, turn of the electricity and remain indoors until the all-clear is given.