I'm noticing a similar issue here with adjusting to the change in temps.  It went up about 15 degrees pretty much overnight, and the humidity went right up with it.  And I am feeling it big time!  Obviously these are temperatures and dew points that I would give anything for in the summer, but right now I'm feeling it because it's so different than what I'm used to.

With all my bellyaching over the weather, those August runs where every single inch of your running gear is completely drenched in sweat by mile 3 of a 10 mile run is not something I miss, at all!

Congratulations, Nata, you did really well, even without being acclimatized.  It sucks  when you're not feeling at your best during a race, but you hung in there.  Great job to you!