Hi,
I just completed a 12 day run from Oregon, west thru Idaho and Montana, then up thru Calgary and west to Banff, Lake Louise, the Ice Fields, Jasper, etc. Absolutely an amazing run. Temperatures ranged from 42 to 95. I wanted to share some of my experiences on riding on those 90+ degree days. I had 2 accessories that made riding in these somewhat difficult conditions very fun: 1) a CamelBack-style water container, and 2) a 'wet vest'.

The Camel Back water container is the backpack-style water bladder with a sipping tube. Every morning I would go over to the hotel ice machine, fill the water bladder with ice and top it off with water. As the day got hot, every 20 minutes or so I would pop free the bottom of my modular helmet and sip an ounce or two of ice cold water. Note that the effects of dehydration are subtle, and at my advancing age, it does sneak up to me. So the continual consumption of sips of water is better than, say, powering down a 12 oz bottle of water at a gas stop every 2-3 hours. There are a number of these available, I bought one at Dicks for around $50

The wet vest is frankly magic. You soak this vest in water, put it on under your breathable mesh jacket, then as you ride the water in the vest wicks off and cools you like air conditioning. Even in the hottest weather the vest stays wet and cools you for 3+ hours. This sucker really works. I bought mine at Cyclegear but there are other providers as well.

Thats's all I got - hope it helps.