Hi Pet,
Yap, it can get quite cold...esp the rooms you'll be putting up in. I remember during my EE, I was in the 6-bedder room (there were 4 of us) and the air con was on pretty low temp. But, as we're all strangers, everybody felt "pai seh" to increase the temp - coz we didn't know who wanted the low temp. End up, all suffered coz all couldn't take the cold...hahaha. Best part - it rained heavily during the night...so it was super cold!
Yap, they're all in air con rooms, so it's good to bring along a sweater/jacket, just in case...