Helmet Recommendations?

[mrlmd1]

They make cooling vests you can wear under the mesh jacket to stay cool. Some of these things have those gel freezer packs in them some of them you wet so you get more evaporative cooling. You can always wet down your tee shirt under the mesh jacket.
One thing you have to be careful about riding in the heat is actually getting dehydrated, from insensible water loss due to evaporation from your skin in the wind. Some riders actually like the windproof or even leather jackets when on a trip to cut down on water loss and they say it actually keeps them cooler in a long ride.
It's not bad till you stop and sit in the sun. For me, even with all the vents open, my helmet and head is all wet, but unless I'm just going around the corner, I always wear it.