Khamseen (meaning fifty in Arabic) is a dust or sandstorm that typically lasts around 50 days, sweeping across many countries in the region. The storms typically blow over Jordan for only a few of these 50 days. They are caused by strong southerly winds passing over arid deserts. Sandstorms have a solid wall of sand at their leading edge; they are usually confined to a shallow layer below calm skies. Dust storms, on the other hand, lift and diffuse light dust particles higher up in the air. Desertification exposes more sand to the wind, increasing the occurrence of such storms. Khamseen can cause minor structural damage, as well as reduce visibility and coat everything with dust.
Large dust and sandstorms usually traverse a number of Middle Eastern countries and may cover all of Jordan. They typically form in late spring.