The bees did not want to abandon the capped brood on the deep frames. I had pulled three deep frames partially covered in honey, to harvest for ourselves, and put the remaining seven deep frames into two deep boxes – with some separation between the frames – and set the boxes on the ground. This was so that the bees that stayed on those frames could return to the hive at dusk. (I did not brush them off into the hive.) However, this morning, even though it was 42 degrees outside, there were four or five clusters of bees on those deep frames trying to keep portions of the capped brood, and themselves, warm.
I moved the boxes to a spot where they would catch the first morning sunlight and warm up the bees. Later in the day, I saw bees fanning the capped cells to keep the brood cool in the direct sunlight.
At about 6pm, I opened the top of the hive and brushed the remaining bees off of the deep frames and into the hive. There was a cluster on the inside of one deep box (not on a frame), however, that I could not brush into the hive.