If I don't turn on the space heater during winter, the basement room temperature sometimes goes to as low as 16 degrees celsius here where the Neumann's are sitting at... hmmmn. Also the sub is directly sitting on the floor, where it can get as cold as 14 to 10 degrees (when extremely cold)! Now, does this mean all my measurements done in the winter cannot be trusted? Well, it's probably a good thing that I wait for the ambient temperature to reach 21-22 degrees celsius now before doing most measurements.
Honestly, I am more concerned about my legs and hands feeling cold than warming up the speakers adequately for my ears' pleasure.
*It would be interesting to know how tropical or dessert hot climates affect speaker measurements. From the klippel graph it looks like just slight bass boost.