1) Dilute 'commercial gatorade type drinks' 50% with water - truly if you don't, you actually LOSE water - 5% sugar solution acually absorbs faster, and 10% may actually USE bodily fluids to ingest, thus dehydrating you further - that came from my Aus Sports Medicine Fedn Sports Trainer course...

2) The heat by itself will not necessarily be the killer - but high humidity will knock you about much more at the same temperature - until you get acclimatised, your body will distress, because the sweating will not cool you anyway in high humidity - it's the evaporation, not just the sweating that cools, but any movement of air will assist, even if the humidity is high.

The Medieval sword & shield guys from NSW & Vic used to be unable to
handle Qld Summer heat - high humidity - so we had to have our Aus wide tourneys in winter for them to cope.... summer further south is less humid than in Qld... :-)