I don't think we'll have quite the problem as last year with temperatures. I just dnf'ed a 600k in DC mostly because of hyponatremia. Not enough salt and too much water. I was also suffering from a cold, but riding well until it got hot. So with a hydration pack in hot weather, that is something to worry about. I am pretty sure I have had lesser cases of that on hot 600k's in the past. I am definitely going to bump up the electrolyte content of my hydration this weekend.