According to the Royal Netherlands Meteorological Institute (KNMI) in De Bilt, there is a white Christmas if a closed snow cover is measured in De Bilt at 9 a.m. on both days. Since the beginning of the last century, this bad thing has happened eight times: 1906, 1938, 1940, 1950, 1964, 1981, 2009 and 2010.
