Understanding that climate explains everything else on this site: the furnace summers, the cold-nighted winters, the spring dust, and the rare but dramatic rain.
Continental, dry and high
Because it is so far from the moderating influence of the ocean, the Najd plateau heats and cools rapidly. Summers are longer and hotter, and winters cooler, than coastal Saudi Arabia at the same latitude. The dry air holds little heat overnight, producing the large diurnal range — often 15–18 °C between a summer afternoon and the following dawn — that is the signature of a high desert.
Rainfall is far too low to support natural vegetation beyond the hardiest desert plants, which is the defining test of a true desert (BW) climate; the “h” marks it as hot, with a mean annual temperature well above 18 °C.
One region, several climates
Although all of the Riyadh Region is hot desert, it is not uniform. The far south, toward Wadi ad-Dawasir and the edge of the Empty Quarter, is the hottest and driest, with the mildest winters. The north, around Majmaah and Zulfi in Sudair, sees the region’s coldest winter nights and a little more rain. The higher western highlands toward Shaqra, Dawadmi and Afif — well over a thousand metres in places — temper the summer heat slightly and collect the most rain and dust of all.
These genuine sub-regional differences are reflected in the forecasts and climate notes for each town and district across this site.