Quote Originally Posted by OakLeaf View Post
I'm a firm believer that you CAN acclimate to heat, but be careful and gradual and smart about it.
No matter how much I ride on hot days, and no matter how acclimated I get in terms of efficient sweating, I will never be able to ride at noon when the heat index is 105 without feeling weak and desperately in need of finding shade immediately or I will completely freak out. Everyone has a limit, and for most people it is probably when forecasters are predicting "deadly heat," like they are this week.

When temps are hot but not as bad as this week, I find a noticeable improvement in my energy levels when I increase my salt intake.

And if I'm riding at noon, I need to have a big breakfast at the very least, possibly also a snack pre-ride depending on how long I'll be riding.

So I'd say it could be combination of things. But mostly, stay out of the sun between 11 and 3 on really hot days.