I went up the the hive this morning to check that the entrance was not blocked by snow. They have plenty of ventilation as the mesh floor provides that but they would not be able to get out and as we've seen they certainly have not stopped flying.
It was surprisingly mild on the terrace considering the conditions and the campus looked picturesque.
The entrance was clear and just a little snow on the top.
Rather than risk disturbing the bees and as there were signs of a thaw I decided not to interfere.