HOUSING MATTERS
Bedding and litter should be of an adequate depth to provide a level of insulation but don't be tempted to stuff the house full of straw thinking it will create a cosy house. Straw can look clean and dry, but it is not particularly absorbent and has a habit of "sweating" when soiled with droppings or muddy feet. This can quickly give rise to fungal growth and the resulting spores can lead to respiratory illnesses in the chickens. If possible it's far better to use shavings or some of the other biodegradable litter products on the market. Be aware that the use of straw can increase chances of mites as mites use the 'tubes' of the straw to crawl into.
FREEZING WEATHER & CHICKENS
Winter can present its challenges for any animal, and it's no different for chickens.
No matter what season it is, providing the optimum conditions for your flock is essential. They may not be producing eggs right now, but invest effort in their upkeep and they will start the new laying period in prime condition.
Despite the chicken's origin as a jungle bird, its evolution and domestication over the centuries has created a hardy creature that can survive freezing winters. Granted, on some days they will elect to spend the majority of the day inside the coop, but I put that down to them having a few more brain cells than we think they have, and actually seem to relish the winter weather.