I've had 4 Ipads from the 1 (got the first week or so), the 3, an Air and now a Pro 12.9. To be truthful, I charge with cases on, (a variety of cases), don't close apps because the Ipad memory handling is very good now, live in NC in the foothills but have used an Ipad all over the state and further south--with no issues regardless of temps. i use mine outside in very hot weather. All of the ipads, to my knowledge (I gave both the 1 and 3 to others, still have the Air for streaming to Apple TV), are still working. I outgrew the earlier ones because I push them, prefer the fastest, love using a split screen and find I can do 95% of my work and entertainment on them instead of using my Macbook Pro. BTW I use a case primarily for easier handling--less for protection.
My recommendation is at least look through the IOS online (IBooks) manual--so many things people are unaware of that are possible on the iPad.