I agree with Brian. Have a look in the brood nest for their actual condition. There is usually quite a bit of stored honey at the tops of the brood frames in a well established colony. This is not to say that they won't need syrup to get through winter, but to consider whether your honey year is over or not. I don't have a measurable fall flow here, and after pulling my honey in late July, early August, the lack of nectar signals the bees to slow brood production. I squeeze them back down to 2 boxes, and leave them to their own devices until it is time to feed them up for winter. If I was planning to harvest a fall flow, I certainly wouldn't be feeding them, unless I found them on the verge of starvation.