Yesterday it was like 90 out-- i went for a 2 hr ride and was pushing pretty hard--although i was constantly hydrating myself, i think i must have gotten sun stroke, as my body has been scorching hot since i came back, and i've been dizzy and natious. How do you serious riders avoid sun stroke---would wearing some sort of bandana or beannie under my helmet help?
Second that. Sunscreen and lots of water is just about the only way to do it. I ride hard though 95-100 degree weather and the only thing that'll get you through is lots of water. I'm talking two 24-32 ounce bottles. Get a light mesh jersey instead of the regular spandex.
We (most of the USA) had a rather cool spring. We appear to be going head-first into a hot summer. I've noticed a heat acclimation problem myself over the last week-- I have trouble with finishing my runs.
I think that it will simply takes a few weeks to get used to it, in the meantime take it easy and drink regularly.
I find that a good helmet visor keeps some of the heat off your face. If you get heat stroke, even with enough water you still may need to find shade or a cool place to lower your temp. Also take it easy if you need to. The water over the head is helpful.