You are correct in thinking you should keep your epoxy in the air conditioned house, but your other problem will be that the wood of the kayak could stay quite warm all night. Expect your epoxy to cure rapidly and therefore mix it in small batches. Before long you'll get a good feel for how much working time you have.

   This is my first post on this forum. I am building a PocketShip and had the same questions concerns. I live in Virginia and the weather is pretty similar. I am keeping my epoxy in the garage and the day/night temperatures are about the same as you stated. I don't think you need to worry about keeping the epoxy in the house, at least during the warmer weather. 

For the heat, I would suggest mixing smaller batches of epoxy. I use Red cups to mix and I usually don't mix anything larger than 1/4 of the cup. I had problems in the heat and using a suggestion on Pocketship.net, I put the epoxy in a cup of ice when it got really hot. That seemed to slow down the curing process. Another suggestion was to pour the unthickened epoxy on the plywood as soon as possible to spread. Basically when it is hot, you need to be in somewhat of a hurry. Don't rush, but don't take your time either. 

If you are using MAS epoxy, check out their table on their website that states pot life and cure times with different temperature ranges. 

Thanks Ron

You think you have problems? This was when I was builfing my Skerry with no workshop or garage to hide away in. That's °C by the way (about 118° in old money).  :)

Thanks for your responses, all very helpful. I will work with small batches and I went to the MAS website and printed the table you mentioned. I am glad I don't have to worry about 118 degress, I think that might make my boat a winter project:)

Mike