I was there in April and I found it very hot. One just had to get used to the heat. Just make sure that the taxi you rent has good airconditioning so that you will have a welcome relief as you move from one temple to the next. I stayed at a pension near Sofitel which was great value @$25/night for two persons and includes breakfast! We stayed for 4 nites so as to take it easy, and we got a chance to try their foot massage which is a welcome relief after a day of trekking around the temples. Bring lots of singles or $5 bills as this is the main currency used locally.