Please, please, PLEASE keep yourself hydrated.  With this heat you should be drinking plenty of liquids - water, electrolyte replacement drinks - and you should be doing this not just the morning of the mission, but all day, every day during this heat - especially if you plan on being outside for any extended period of time.  If overheating might be a factor, please do not hesitate to arrive in your cage.  Remember - we are here to stand tall and silent, not fall flat and loud.