I've gotten surprisingly good results from eggs that were stored on the kitchen counter (it's stone, so rather chilly) in an egg carton so long as the house temperatures were between 55 and 70 degrees: about a 90% hatch rate under hens. When they got above 70 degrees, things tailed off a bit: with eggs under hens, of eggs that candled as fertile and developing at 4-6 days, we got 4/4, 5/6, and 5/8 in the past month and a half. The house had been hitting 70-73 degrees for a few hours each day through most of that time, and as the weather warmed and the house spent longer at or above 70 degrees, the hatch statistics grew poorer. Still, I was surprised at what those eggs had been able to tolerate!
But hens don't always go broody when I need them to, which is why I bought the incubator, and I've had some trouble getting a good hatch from it. So I figure that I really should learn how to store my eggs better, so that they aren't affected by a too-warm house.