As for the weather, would you rather have rain or heat?
Heat. No question. And I'm about to get plenty of it when I start heading south to Ontario later today on the Hayabusa.... dashing to the Finish Line to help Mr. IBR Photo Deity to score riders.
With all due respect to Dale, I don't see it as quite a "set in stone" answer. It depends.
Heat can be a very insidious danger. It can kick your *** before you think it's gotten bad enough to take measures to further
protect yourself. Even a slight physical heat event can make riding impossible until you recover and that will take some time
in a cool area, out of the heat. You need to be in tune with your body and with the program in general to catch the onslaught
of heat affecting you before it's too late. Rain is alot less the hidden danger.
I don't think rain causes me near the same gravity of issues until the rain or standing water is bad enough to affect
the control of the bike and maybe the functioning of some electronic farkles. Unless rain is at it's very heaviest for extended
periods, I think heat is more likely to put you into a "no go" sitiuation.