The Shamal
Shamāl is simply the Arabic for "north". It is also the name of the northwesterly that runs the entire length of the Persian Gulf, and it is the most consequential wind in this region — it raises the dust that closes the airports, it sets the sea state from Basra to Hormuz, it cools the Gulf coast and it drives the swell that reaches Oman. If you learn to read one thing on these maps, learn to read this.
The geometry that makes it
The Gulf is a 1,000 km trench running northwest to southeast, walled on the northeast by the Zagros — a mountain range that rises to 4,000 m within 100 km of the water. Any northwesterly flow entering the basin is squeezed between that wall and the Arabian plateau and accelerated down the axis, so a moderate synoptic gradient over Iraq becomes a strong wind over the Gulf. The channel is why the Shamal is stronger than the pressure pattern alone suggests, and why it is so consistently aligned.
Two different winds with one name
Winter Shamal
Frontal and episodic. A mid-latitude trough crosses Türkiye and the Levant, a cold front sweeps southeast across Iraq, and cold air pours down the Gulf behind it. Wind reaches gale force, temperatures drop sharply, and the dust is lifted along the frontal line and behind it.
These are the events that strand shipping, close Kuwaiti and Iraqi airports for a day at a time, and generate the largest waves the Gulf sees — a fetch of a thousand kilometres in shallow water builds a short, steep, unpleasant sea.
Summer Shamal
Not frontal at all. It is the persistent gradient between the Arabian heat low and the pressure over the eastern Mediterranean and Iran, reinforced every night by a low-level jet that mixes down to the surface each morning. It blows almost without interruption for several weeks.
In Iraq and the northern Gulf its long, dependable early-summer phase has its own name — the Simoom or Bad-i-sad-o-bist, the "wind of a hundred and twenty days", which in Sistan on the Iran–Afghanistan border blows from late May to September with a reliability you can farm around.
Reading one on this site
- Start with pressure. Open the MSLP map with isobars on. A winter Shamal is a trough over Türkiye and the Levant with a ridge building behind it into Iraq; you are looking for the isobars over the Gulf to turn northwest–southeast and pack together.
- Check the air mass. The 850 hPa temperature tells you whether cooler air is genuinely arriving or the surface wind is just moving hot air around. A winter Shamal shows a clean cold advection tongue down the Gulf; a summer one usually does not.
- Then the wind itself. The 10 m wind map with the arrow layer switched on. The colour bands break on the Beaufort scale, so the step from green to yellow is force 6 to 7 — the point at which dust emission over Iraq becomes efficient.
- Then the dust. Switch to GFS and open surface visibility. Nothing here models dust directly, but a visibility collapse over dry desert with a strong northwesterly is a dust signal — and it is the earliest one a free model gives. See the dust page for the dedicated forecasts.
- Then the coast. The wet-bulb map. A Shamal ventilates the Gulf coast and drops the humidity that makes summer there dangerous — a strong summer Shamal is genuinely a relief on the Emirati and Qatari coast, even though it raises the air temperature.
The region's other winds
Kaus / Sharqi
The southeasterly that precedes a winter Shamal — warm, humid, often carrying low cloud and the region's best chance of rain. It backs sharply to northwest as the front passes, and that windshift is what a Gulf mariner watches for.
Khamsin
Hot, dry, dust-laden southerlies drawn ahead of Mediterranean depressions tracking east. The name means "fifty", for the roughly fifty-day spring season in which they occur. They can lift temperatures in Cairo or Jerusalem by 15 °C in hours and fill the sky with Saharan dust.
Sharav
The same phenomenon as the Khamsin under its Hebrew name, and a genuinely serious heat event on the Levantine coast — where a population acclimatised to a Mediterranean climate meets desert air with almost no warning.
Nashi
A cold northeasterly draining off the Iranian plateau, usually short-lived and overnight, and locally sharp enough to matter to small craft in the northern Gulf.
Khareef
The southwest monsoon's edge striking the Dhofar escarpment. Upwelling cools the sea off Salalah to 22 °C while the Arabian interior is at 48, and the resulting persistent drizzle and fog turn a desert coast green for three months. It is the most extreme microclimate on this map and the reason Salalah has a tourist season built entirely around cloud.
Sea breezes on the Gulf and Red Sea
Not exotic, but the field a 28 km global model most reliably gets wrong, because it does not resolve the coastline that generates them. The Gulf sea breeze is what carries the dangerous humidity inland from Dubai and Doha each afternoon, and resolving it properly is one of the clearest arguments for a mesoscale model over this region.