The Arabian Desert has a subtropical, hot desert climate, close to the climate of the Sahara Desert ; the world's largest hot desert. In fact, the Arabian Desert is 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 100 mm, and the driest areas can receive between 30 and 40 mm of annual rain. Such dryness remains very rare throughout the desert, however. There are hardly any hyperarid areas in the Arabian Desert, in contrast with the Sahara Desert, where more than half of the area is hyperarid (annual rainfall below 50 mm). The sunshine duration is very high by global standards in the Arabian Desert, between 2,900 hours (66. 2% of the daylight hours) and 3,600 hours (82. 1% of the daylight hours) but is typically around 3,400 hours (77. 6% of the daylight hours), which clearly indicates clear-sky conditions prevails over the region and cloudy periods are just intermittent. Even though the sun and moon is bright, the dust and humidity has a lower visibility for the traveler. The temperatures remain high all year round. Average high temperatures in summer are generally over 40 °C (104 °F) at low elevations, and can even soar to 48 °C (114. 8 °F) at extremely low elevations, especially along the Persian Gulf near the sea level. Average low temperatures in summer remain high, over 20 °C (68 °F) and sometimes over 30 °C (77 °F) in the southernmost regions. Record high temperatures are above 50 °C (122 °F) in much of the desert, due in part to very low elevation.