Boiling water is at 100C at standard pressure full stop. It is not affected by weather (humidity or air temperature). It is not affected by location unless your change of location involves a change in altitude which accompanying pressure change.
It varies in a range of about +5% to -5% of average pressure.
Anyway, I think people are vastly underestimating just how far scientists where calibrating things back then. Clock making for example cares deeply about the current temperature.