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Assess the activities you’re planning for your trip very carefully. Winter clothing will take up quite a bit more room than summer clothing, of course, so you’ll need to strategize based on what you’ll be doing.  Don't forget a medium-weight jacket. Even though Florida has a generally warm climate, the lows in the winter average in the 40s, so you’ll need a jacket in the evenings and early mornings. Throw in a scarf and a hat if you’re particularly cold-natured. You probably won’t need gloves, but they can’t hurt. Pack layers that you can wear more than once if possible. For example, a neutral colored sweater that matches several outfits will help a lot. With an average low in the 40s in midwinter, Florida can get quite chilly. You probably don’t need your bulkiest sweaters, but you can’t go amiss with a pair of jeans and a few long sleeve t-shirts. Particularly if you’re going to be doing any activities that involve a lot of walking, you may get a bit warm in long sleeves, even in the winter.  You probably won’t need any shorts unless you’re going to be very far South, since the average winter high is 60 degrees, but if you’re a hot-natured person, you could consider bringing a pair. Depending on where you’re going in Florida, odds are pretty good that you’ll encounter at least one downpour. Most cities there get between 90 and 140 days of rain per year. You will probably want an umbrella or light raincoat. Take a close look at the forecast to decide if galoshes will be worth the space they take up.
Bring warm layers. Pack long pants and long sleeves. Include some short sleeve shirts. Pack for rain.