I live in Phoenix. Sometimes the temperature in my backyard gets to over 120 degrees. I have found that even when I take the eggs in three or four times a day, they will not hatch successfully. Those that did go all the way had deformed feet. We finally decided it was not worth trying to hatch in the summer.
The eggs seem alright to eat as long as the shell is not broken. When you do the float test, the sinkers are alright to eat fried, but the floaters better be used for baking. Crack the eggs into a cup and look at them before you throw them into the mix. If they really float real well, trash them.
Also, eggs we bought through the internet would not hatch successfully. Just sitting in the postal van must have been like sitting in an oven.
Rufus