Another change of plan so there is a big chance I won’t make it this March. But I will keep this thread, and thank you for all your inputs!
“Some things never change” is that I will do something Disney real soon
I've been to FL many times - approx - this time of year. As others have said, temps can be variable.
IME, odds are fairly high that you will see at least one warm day, and at least one cooler day/evening.
Often a good strategy is to wear shorts in the AM with a jacket, take it off mid-day, then swap to long pants at night.
Do keep in mind that the WDW pools (and Universal) and many other hotels are heated. Hot tubs can be pretty nice.
Outside of swimming, there is much to do in the Orlando area outside of the theme parks, if you so desire. This can be a fun time to explore the resorts and Disney Springs. I'm not sure when the Easter eggs go up in the deluxe hotels, but they are fun to see. Easter is April 5 this year, so at least some will probably be on display before your trip ends.
You said early March. This is still orange season. If you have transportation. With a car you can go all over and see all sorts of things. A day trip to the Everglades is an option, and it will likely be warmer the farther south you travel. Just an hour north of WDW, is Ocala, and a little further is Silver Springs State park with glass bottom boat tours. If you are a fan of WDW, you owe it to yourself to visit Silver Springs for the boat tour at least once. Two hours to the east, St. Augustine is really neat.