Mine slow way down (one year even stopped, but there were feed issues that year) in the fall when they molt. This starts around mid Sept.- early Oct., and egg production is really slow until shortly before Christmas, when it suddenly picks up again. This is also about the time I stop seeing raggedy looking hens, so when they finish growing new feathers, they lay steadily again. This year, I added a light on a timer, to come on at 4 am. This increased the light to a bit over 12 hours, not the 14 that many suggest, but well over the 8 or less they've been getting of natural light. I added this about 3 weeks ago. 
Many folks have posted that egg production increased drastically, almost overnight, when they added light. For me, it made no difference at all. Then, about a week ago, just before Christmas, like always, they started laying more again, just like previous years when I didn't add the light. Because I don't want a sudden change to less light, I'm changing the timer gradually until I can shut it off altogether. I'm going to try a different feed formula next year, to see if I can speed up the molt. More protein, more sunflower seeds, some fish pellets, etc. 
Molting BTW, IS NOT a "rest period". They are expending a great deal of protein and energy re-growing a new set of feathers, that's why they slow down or stop laying, 
because it takes a lot out of them. They not only have to grow new feathers, it takes more energy for them to stay warm while they're half-naked.
Our weather here is weird, we have nice balmy spells throughout the winter, interspersed with bitterly cold hard freezes. I don't feel like my chickens really get a chance to become acclimated to severe cold, because the changes are so frequent, and so sudden. 
Recently, after several nights of temps above freezing, suddenly one night was 4F. On these bitter cold nights, I leave a high wattage heat bulb on, in a clamp-type lamp that I can aim so it's not blinding the birds on the roosts. I found that if I aim it so the roosts are only dimly lit, and turn the light on a couple of hours before dark, they go on in and settle down as usual. If I forget, and try to turn it on later, they get all freaked out and agitated.
They still get out in the daytime, regardless of the weather, If it's too nasty, they stay inside of their own accord. But they have the option to wander outside if they want, that keeps them from getting agitated from confinement. In bad weather I only open the run-pen doors to give them access to pasture, and they go in and out via the small chicken doors, and I leave the big main door closed, both for warmth and so it doesn't rain into the coop. That way they can still free-range if they want, but the coop stays warmer and dryer. They 
will play in the snow when the sun comes back out. They even wallow in it and take snow-baths!
We also use an immersible water de-froster (they have them at 
TSC) in one of those black rubber tubs they sell for horses.