Does he provide a link to the data?
He has a graph of lowest temps that goes back to 1945 with a ten year moving average.
Unfortunately, Friends of the 500th does not post its data online, but you can always join the group and get the newsletter mailed to you. Dave has a column about weather in every issue.http://www.fws.gov/canaanvalley/CVNWR%20Friends.htm
PS An individual membership in the Friends of the 500th costs $10, and a family membership, $20.
PPS Another bellwether for temps in the valley are birds, and the local bird expert, Casey Rucker, often has a column in the newsletter. This winter he reports that he's seen the Northern Shrike on Cortland Rd (a rare winter visitor), but no Bohemian Waxwings--an artic bird not to be confused with the very common Cedar Waxwings that occasionally ventures as far south as PA, and on very rare occasions, the CV.