It's absolutely OK to let your chickens out in the winter - if they'll go. Mine aren't too fond of snow, so they generally don't wish to go outside if there's snow on the ground. I don't know where you live, or how cold it gets, but I will also go out an a limb and say that you don't need a heat lamp for them, either. They have their built-in down coats on all the time. They can't take them off when they go from outside to inside. Constant temperatures are better than going from hot to cold to hot again. Chickens are much more tolerant to cold than to heat. Good ventilation in your coop is also a must. Cold and dry is much better than warm and humid. Frostbite is more likely to occur in humid conditions.
the temperature is dropping before 100 around here now (Phoenix, AZ) .. this will be my hens' first arizona winter.. but are out and about just like any other day
Absolutely - I have had flocks in areas where winter means feet of snow and sub zero temperatures and have never changed my routine of leaving the pop door open dawn to dusk to allow them to opt in/opt out of enjoying the great outdoors. Generally speaking unless it is actively precipitating or extremely windy they will opt in to going outside, even on the coldest of days. Chickens are very well designed to withstand temperatures humans consider unbearable - this is thanks to their wonderful insulating down and well paced outer feathering (which is why windy days are not a favorite as it disrupts the layering and makes the birds uncomfortable by stirring things up when blowing against the grain of their plumage. As noted above, some birds are more finicky than others about walking in snow or on ice - if you find your flock is reluctant to step outside on to covered ground, toss out a layer of shavings, hay, straw, etc. My last flock would line up at the pop door, heads poking out looking towards the house, and wait for me to go out and cover any newly fallen snow with a few flakes of straw -- but as soon as the straw was down they were all outside for the day.
I open the run door that leads to their area to free range and if there's snow on the ground they only go as far as the dry land is but will peck at the snow around it. It's so funny to watch them
Mine like something like hay or straw to stand on outside. Standing directly on snow on really frigid days can cause frostbite on their feet.
