We farm in the mountains of northern Vermont and farrow hundreds of pigs outdoors year round. We don't have barns. We do make wind blocks, one walled, two walled and such sheds. Greenhouses are great. Most of all they need protection from the wind. Even a few large hay bales do the trick. Next they need dry bedding. Wetness sucks the heat away. January is actually better in this way than November. Their mother is 103°F - she's a heating pad. A good, experienced sow farrows fine in the cold weather. She does need privacy so that other pigs don't snuggle up to her. Naturally they go off in the brush to seek privacy but this is harder to do in the winter.
Good luck with your unplanned pregnancy.
Cheers
-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop
project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa