We've been following the progress of our first hive's overwintering by looking for dead bees (not many) and listening for the hum from within (steady volume and pitch). This past weekend was so cold in Baltimore (5-10F and windchills down to -5 or -10F) that our neighbors lost water pressure from their underground water meter actually freezing. We've been here since 1989; the water freeze is a first since at least then.
Tonight we checked on them to see how they fared over the bitter frozen qeekend and found (1) many more dead bees inside the entrance (two layers, my 10 year old son thought) and (2) the pitch of the hum inside was noticeably higher. I'm interpreting the pitch change as indicating a smaller cluster from fewer and fewer surviving bees.
And we're hoping that February is milder than January.
January in the Boston area was the coldest in recorded history, many days in the single digits. Today we had a beautiful groundhog day with the temperature almost 40 and I had many bees flying around the hive. A sign of spring.