The Arabian Desert has a subtropical, hot desert climate, similar to the climate of the Sahara Desert; the world's largest hot desert. The Arabian Desert is actually an extension of the Sahara Desert over the Arabian peninsula. The climate is mainly hot and dry with plenty of sunshine throughout the year. The rainfall amount is generally around , and the driest areas can receive between 30 and of annual rain. Such dryness remains rare throughout the desert, however. There are few areas in the Arabian Desert, in contrast with the Sahara Desert, where more than half of the area is hyperarid (annual rainfall below ). The sunshine duration in the Arabian Desert is very high by global standards, between 2,900 hours (66.2% of daylight hours) and 3,600 hours (82.1% of daylight hours), but it is typically around 3,400 hours (77.6% of daylight hours), thus clear-sky conditions prevail over the region and cloudy periods are intermittent. Even though the sun and moon are bright, dust and humidity cause lower visibility at ground level. The temperatures remain high all year round. Average high temperatures in summer are generally over at low elevations, and can even soar to at extremely low elevations, especially along the Persian Gulf near sea level. Average low temperatures in summer remain high, over and sometimes over in the southernmost regions. Record high temperatures are above in much of the desert, due in part to very low elevation.