So there's a website in the Netherlands where people can report their sightings of all wildlife; from birds to herps to insects.

The 30th of January, 2009, a Eurasian Viper was reported, which I believe is the first report on that website of one during January, ever.

"Een jong mannetje, lengte ongeveer 20 cm; laag heerlijk in de zon op een nauwelijks ontdooide bodem bij een temperatuur van + 1 graad Celsius."

Translation:

"A young male, length about 20cm; basking in the sun on a barely thawed ground at a temperature of 1 degree Celsius."

V. berus is one of my favorite all time species