Not sure if I have a specific critical temperature but I don't do well with heat even at the best of times so think I might park any plans I may have been formulating for the coming week!
Can't see any problem asking the girls if they've got the things you need though as I'm sure every single one of them will have been asked for things much more unusual than air-con! 
Likewise I don't like the heat and was hoping to have a punt this week however i've been to the gym today for a full session and needed to have a couple of extra rest breaks part way through my normal exercise regime.
Jumped in the car to come home and even once the air was flowing in the front so the sensor wasn't giving a false reading from being sat in the sun it was 29 degrees

Only 23 degrees in the lounge now i'm home but the usual flats most of the Thai girls I see always seem hot as the sun beats in some of them and there's no fucking air con

I sometimes struggle to perform if i'm too hot and have wasted my punting tokens far too often so i'm thinking I may just save my money and sort myself out with some porn this week which i've not done for a while, as they say a change is as good as a rest

Goodness how the guys further down South / London etc cope