The first map shows all the weather stations in the contiguous U.S. which have reported snowfall since August 1, 2018. The second map shows everywhere which had snow on the ground during its last data update.1
The maps were last updated on 2019-04-16. They include all stations which have reported since 2019-04-09.
If you see a snow dot in a particularly improbable place, I suspect it’s the result of a data entry error.↩