Winter ice/snow wiper blades??

I don't think you'll need winter blades in Ft. Pierce, FL.

 

There are now two types of "winter blades". The old style, with flexible rubber covers that make it hard for ice to build up on the frame are:
Trico #
26" size for drivers side - 37-260
18" size for passengers side - 37-180.

The "new" style are "silicone rubber" and very thin. They don't have a metal backing. They are also supposed to leave a silicone residue on the glass, making it like you're using Rain-X. I don't have numbers for those, but check your auto parts supplier. The sizes are as above.
As far as I know, there is no non-Toyota replacement for the rear wiper unless you change the arm.

I wouldn't bother going to the Toyota dealer, they seem clueless, as there are no parts "listed" for the Prius. They tried to foist a 22" drivers side one from the Camry on me! They have nothing for the rear.

 

Another thing I would recommend is the
"Rain-X De-icer Windshield Washer Fluid"
I have it in my car and it works like a charm!

 

I just walked into my NAPA store, and walked out with the correct replacement winter blades. I live in western NY, so I get the full rubber coated ones. They work on the other cars, they will work on the Prius.
Factory wiper blades are not designed for "all weather".