I don't know ... I think you can acclimate, but only if you have consistent exposure. It wasn't an issue for me as recently as last year, though I haven't been able to yet this year.
My first husband served in the Air Force in Thailand, and he talks about coming home to Ohio in August, 85° and 70% humidity, and needing a blanket because he was so cold.
But the bottom line is that you and your friends aren't acclimated, and there's nothing wrong or weak about that. You obviously made the right decision and you should be comfortable with that IMO.
Speed comes from what you put behind you. - Judi Ketteler