Got it covered :) The run in July is the Loonies Midnight Marathon - starts at Midnight! :) no sun to contend with :) but, also keep in mind the body has some impressive heat acclimatization processes that usually fully kick in within 14 days. Many risk can be abated if you know what you're doing - http://www.sportsci.org/encyc/heataccl/heataccl.html is a pretty good site if you want to learn more