No. Not at all. Chickens should need any heating at all in that climate. I know of someone who successfully raises them in three sided sheds, in Iowa, where it gets down to -30 F. They lose eggs, which freeze before they can be collected. But overall the birds do fine.

Perhaps for your climate, the concern should more be, will they have sufficient shade during the hot time of the year? But again, chances are that they will do just fine. Chickens are generally very tolerant of heat, as well, as long as they can have shade and water.

George
Tahlequah, OK

Our chickens are very happy and healthy here in a zone 6 microclimate. They free range no matter the temps/precip and go in their simple coop only to roost. We have no electricity or insulation out there - just plenty of windows, 2x4 roosts, snug nest boxes and great ventilation. To all those worried about frozen water I wanted to mention my experience after over thinking/worrying... I ended up with a shallow rubber tub that I refill/dump ice from each morning/afternoon... That works fine. Had thought I'd need heaters etc etc. Like my horses, chickens seem happy living a "somewhat natural" lifestyle without costly gimmics/extras! ;-)

Gtes pretty cold here, below zero often. My coop aint no where near draft free, and my chickens do fine. Do lose quite a few eggs to freezing though.