Saudi Arabia spans a large area of the Arabian Peninsula, resulting in a climate that is predominantly arid across most of its landmass. Situated within the subtropical high-pressure zone, the country experiences intense heat and a profound lack of moisture. This expansive geography creates substantial variations, resulting in a complex mosaic of hyper-arid conditions alongside pockets of more moderate weather.
Defining Features of the Saudi Climate
The overarching climate classification for most of Saudi Arabia is the Köppen system’s hot desert category (BWh). This designation indicates extremely low average annual precipitation and high temperatures throughout the year. Average annual rainfall is scarce, often less than 100 millimeters across the central and northern regions, sometimes consisting of just one or two heavy thunderstorm outbursts.
A defining characteristic of the interior is the huge diurnal temperature variation. Daytime heat rapidly dissipates after sunset due to the dry air’s inability to retain thermal energy. High temperatures, often averaging 45°C in the summer, are coupled with a high annual evaporation rate, ranging from 2,500 to 4,500 millimeters per year. This rate is far greater than the precipitation, cementing the land’s aridity and resulting in a “dry heat” where low humidity offers no moderation.
Major Regional Climate Zones
The climate shifts dramatically when moving from the central plateau to the coasts and mountains. The Interior, known as the Najd, is a vast continental region experiencing the most extreme thermal range. Summers are scorching, with maximum temperatures frequently exceeding 45°C, while winters can be cold, sometimes dropping close to freezing in northern areas.
Along the coasts, the climate is moderated but often uncomfortable due to high humidity. The Red Sea coast (e.g., Jeddah) is characterized by very high humidity and warm temperatures year-round. The Persian Gulf coast experiences hot, humid summers but slightly cooler winters, as prevailing northwesterly winds originate from the drier Iraqi desert.
The Southwestern Highlands, encompassing the Asir Mountains, offer a significant contrast. The higher altitude results in cooler temperatures and higher annual precipitation, sometimes reaching 400 to 600 millimeters per year. This region benefits from a seasonal monsoon influence, allowing for summer rainfall and creating a semi-arid environment.
Seasonal Extremes and Weather Events
Saudi Arabia’s annual cycle is dominated by a long, intense summer season lasting from May through September, with peak heat in late July and early August. During this period, the average maximum temperature across the interior hovers around 45°C, and temperatures exceeding 50°C are common in the Rub’ al Khali desert. The mild winter season, peaking between December and February, offers a respite with average temperatures around 20°C, though the far north can experience frost and occasional snow.
The most notable episodic weather phenomenon is the Shamal wind, a strong, hot, and dry northwesterly flow that blows almost continuously during the summer months. This wind is the primary mechanism for generating massive dust storms, often referred to as haboobs. These storms significantly reduce visibility and cause respiratory health issues, often beginning in late May and subsiding by mid-August.
Despite the low overall rainfall, flash flooding is a concern. Rainfall often occurs as rare, intense cloudbursts, overwhelming the dry riverbeds known as wadis. The sudden, sharp rush of floodwaters through these drainage systems poses a significant hazard, especially in urban areas that have encroached upon these natural floodplains.