I did the math:
Room temperature is often defined as 20 degrees Celsius (although I remember it being 23C in some old textbooks).
20+16.6 is 36.6 which is the normal temperature of a human body.
20+18.6 is 38.6 which is above normal temperature, i.e. fever.
AFAIK ~42.0 degrees is lethal.
meanwhile in multiple slavic languages pretty much the same word (датчане, данцi, datčáne, …) refers to Danes.