Summers are extremely hot, with coastal temperatures reaching 46°C (115°F) and those in the interior even higher. The winters are quite warm; the average annual temperature in Masqat is 29°C (84°F). The climate of the coastal plain and mountains of Dhofar is moderated by the monsoons that deposit about 760 mm (about 30 in) of rain annually on the south side of the mountains and about 150 mm (about 6 in) along the coast. Parts of the ?ajar Mountains receive up to 460 mm (18 in), while Masqat receives less than 100 mm (4 in). Flash floods can occur when sudden, heavy rains run off the mountains and down the wadis, or valleys. In Oman’s interior summer winds cause large sandstorms and periodic droughts occur. In the south monsoon winds can endanger shipping.