If the peanut butter has remained sealed and has never been opened then the peanut butter should be safe in the heat.
I keep peanut butter in my garage that is always hot during the summer months because I have an extra pantry out there where I store extra food that I buy such as canned goods and yes peanut butter.
The peanut butter has always been just fine in the heat and has never gone bad on me.
If the peanut butter has been opened then it's best to keep it out of the heat though but you don't have to refrigerate it.
The worse thing that will happen to peanut butter in the heat is that it possibly melts but after it cools off it should return to normal peanut butter consistency.
Peanut butter is pretty indestructible as well and as long has it has no mold in it or has any bad smell to it then the peanut butter is good and safe to eat.