Okay, we know that already but I'm really surprised how much they do to warm up their hive.
All day its been alternating between snow and rain here, temps have been in the mid 30's.
Just out of curiosity I took my outdoor wireless thermometer and stuck it inside the mostly empty top medium box of my hive. There where bees down below the meter but this is the air temp in an empty box, not cluster temp.
Outside temp, 34.5º
Inside hive temp 60.2º
I can only guess what the cluster temp is but I think I'm going to buy another wireless thermometer and stick it in a frame and let the bees draw comb around it and integrate it into the hive so this winter I can see what the bees core temp is.
This also got me wondering if anyone knows what temperature kills adult bees and what how warm brood has to stay to remain viable?