Electric motorcycles deliver vastly different range depending on operating conditions.
That's bad because it's hard to give a good, general answer for range. Zero claims 85 miles of range for the S ZF11.4 at a constant 55 mph, and that seems to be about right for a light rider on flat ground. Headwinds, additional rider or cargo weight, hills, cold temperatures (are you riding year-round? if not, how low will you go?), and eventually battery degradation will all eat into that range.
However, it's also good in a way because you have a lot of tools to extend range somewhat if you pay attention. For example, if you're running along at 60 mph and you see that your consumption is unusually high one day, maybe you lower your speed to 50 mph or detour to a lower speed route.
70 miles at 40F at an average of 50 mph (presumably meaning some at 30-40 mph, some at 60-70 mph) and lots of hills is probably pushing it pretty close on the ZF11.4 battery. You could probably make it, but I'd recommend getting the larger battery.