January deep freeze

I go out regularly (about every other day) to check on the hive. We've had a lot of snow lately, and I've gone out to make sure the entry-ways are clear of snow. Each time I go out I find about 4 dead bees that have been pushed out onto the apron of the hive. This tells me the bees are still ok inside, regularly clearing out the dead bees. We have been experiencing some very cold January weather here in Iowa, with wind chills tomorrow morning in the minus 30 range (up to 15 below F actual temp). I have been following the bee listserv and there are some very interesting reports by some posters, including one who opened his hive to check the status even when the temps were in the single digits farenhiet. He is an an experienced beekeep and seems to know what he is doing but it seems to go against everything else I've read, most of which says to open a hive in those temps is a formula for disaster, but he seemed to take it in stride. Some posts are concerned even about the vibrations from nearby snowmobiles causing the hive cluster to break up, which would cause them to drop in temperature and suffer as a result. Others poo-poo those concerns, such as the person I described above. I know I certainly do not want to open the hive until spring, but am not concerned about my clearing away the bees on the hive entrance anyway.