I'm not sure where Port Charlotte is but I can tell you about the weather. It should be consistent highs in the mid to upper 70's and lows in the low to mid 50's(for the next week). This is what I found the last time I checked the NOAA.

When coming to Florida, bring a variety of clothes. We switch from pants to shorts, shorts to pants, all the time. It's usually pretty warm, with the sun, during the day and cool at night. You'll need a light jacket or sweater for that. I would bring the bathing suit if I were you. Coming from up north, you'll probably find it warm enough to swim in some places comfortably(alot of the pools here are heated). I hope you enjoy your trip!! Let us know how it went.