In his talk at the CRFG Fruit Festival last year, Jon Verdick had this to say about it ( http://webebananas.com/FESTIVAL%20OF...%20Handout.pdf
Joe Real's Cold Hardy List, from most hardy to least:
Generally. Red bananas are less cold tolerant (Tall Red, Dwarf Red,
Cuban Red, Kru Red Iholena, Red Green, Dwarf Red Green, Rose), though
some green bananas are fairly tender as well, such as Kumunamba and Kofi.
Most Reds will barely survive mid 40's for extended periods. Flowering, in winter (induced by an unusually warm week), or after a long winter can impact fruiting (size and quantity).