In that region, the natural growing season is late April to early October at best, and there were a number of CSAs in operation. The farmers utilized season extending methods, crops naturally adapted to that type of climate & early maturing cultivars.
Having a large urban population center nearby which was receptive to the concept certainly assisted in its early development. So, this may not be possible where you're located. But I wouldn't rule out the idea strictly due to climate. After all, they even grow veggies in parts of Alaska.