in Thoreau’s Journal:

Hear that there was a flock of geese in the river last night. See and hear song sparrows to-day; probably here for several days.

It is an exceedingly warm and pleasant day. The snow is suddenly all gone except heels, and — what is more remarkable — the frost is generally out of the ground, e.g. in our garden, for the reason that it has not been in it. The snow came December 4th, before the ground was frozen to any depth, has been usually deep, and the ground has not been again exposed till now. Hence, though we have had a little very cold weather and a good deal of steady cold, the ground generally has not been frozen.