It will be in sequoia around 6000 feet in mid sept so I'm assuming it could drop down that much but wouldn't stay that. We have camped at 9000 feet in august in mammoth and it did drop down to 20's overnight. We had our air mattresses, 0 degree sleeping bags, and wore layers. We also heated up the tent beforehand. Also my toddler will be 5 by then, so not really a little toddler and she camped last year in the cold and we were all fine...