Voor zo ver ik weet is dat de normaal die hier gehanteerd wordt. Sterker nog, dat weet ik zeker. Waarom, dat weet ik niet. De WMO zegt er het volgende over
Congress, through Resolution 16 (Cg-17), endorsed the recommendation of CCl-16: "The Climatological Standard Normal be calculated every 10 years at the start of every new decade having year digit 1; to serve as the updated official Climatological Standard Normal; that it applies to the most recent 30-year period, with 1981–2010 being the new current standard; and that for specific purpose of long-term climate change monitoring, the period 1961–1990 be retained as a reference period in perpetuity or until such time as a compelling scientific case to change it arises".
Ik moet het dus even aanpassen naar 1961-1990 (1960 is foutief).