No Cab here. I’m in Northern Wisconsin. I have all northern hybrids. Marquette, Petite Pearl, Frontenac, Itasca, and Brianna.grapevines can handle -6 Fahrenheit (i.e. -21 Celsius). If your Cabernet Franc are grafted maybe a bit lower. What are you growing and why?
It’s not the low temps that bother me it’s the -12F to 45F in a week… and there is lots of winter left so we could be below zero again soon.