Why am I getting so few eggs?

We have about 10 layer hens, and 4 are for sure old enough to be laying. The ones that are old enough are barred rocks. 2 are marans, one is a silkie, and one we think it a ameriaucana. We were getting 2- 3 eggs a day all summer, but now we are only getting one a day. I know that the lack of sunlight and cold weather affects them, but I hoped for more than 1 egg a day.
Thanks
They are all kept in the pen/coop, and fed layer pellets or crumbles.