Hi Robert! At the end of June the temps are very variable depending on the year (some years had been very hot and other cooler and wet) and the elevation you choose to sleep at - but I had woken up to frost on the trail on two occasions on the while racing the Epic in years past - so I would say average nightime temps are likely around 5-10 degrees Celsuis but it can drop just below freezing.. Many tent, many bivy, some have done hotels only.. It all depends on fast you want to go, how much weight you want to carry and what your preference is.