One day the horizon disappears, the volcanoes turn into ghosts and the sky takes on the yellow tint of a Western: welcome to the calima (Saharan dust haze). It is neither fog nor pollution: it is Saharan dust in suspension — ultra-fine particles that the east wind lifts in the desert, just 130 km away, and carries over here, often with hot air. It usually lasts two to four days, sends thermometers up and visibility down. Is it a nuisance? A little, above all for people with asthma or allergies: on such a day, better indoor plans and plenty of water. Is it dangerous? Rarely — although in February 2020 a historic calima went as far as closing every airport in the Canaries. And in exchange it delivers the most dramatic sunsets of the year.
The calima (Saharan dust haze) is the meteorological reminder of a fact the beaches make you forget: Africa is right next door. Barely 130 kilometres separate Lanzarote from the Saharan coast, and when the atmospheric circulation reverses — when the humid north-east alisio (trade wind) gives way to wind from the east or south-east — the island receives the direct breath of the largest desert on the planet.
The mechanism is pure atmospheric physics. Over the Sahara, windstorms lift millions of tonnes of mineral dust — microscopic particles of clay, quartz and iron. That dust rises and travels in a layer of dry, warm air that scientists call the Saharan Air Layer, capable of crossing the entire Atlantic (Saharan dust fertilises even the Amazon). The Canaries, by neighbourhood, receive the concentrated version: when the wind blows from the east, the dust cloud covers the islands, visibility drops — from the 60 km of a clear day to 10, 5 or under 3 in strong episodes — and the sky adopts that characteristic ochre-yellow palette. Since the air comes from the desert, the calima usually arrives with rising temperatures: the hottest days of the year in Lanzarote are almost always calima days.
How often does it happen? Several times a year, in any season, with greater frequency and intensity in winter and during summer heatwaves. A typical episode lasts two to four days and takes its leave when the alisio resumes its shift and "sweeps" the air clean. The weather services give advance warning (look for "calima" or "polvo en suspensión" in the AEMET forecast), so it catches nobody by surprise who checks the outlook.
And what do you do on a calima day? With common sense, life goes on almost as normal. People with asthma, COPD or respiratory allergies, small children and the elderly should avoid intense outdoor exercise and consider a mask if the episode is strong; everyone benefits from drinking more water and closing the windows. Serious sport is postponed or moved indoors. And it is the perfect day for the luxury plan B: Cueva de los Verdes, Jameos, museums, the bodegas of La Geria — the underground island and the wine island pay no attention to dust. The photographers, meanwhile, go out hunting: the filtered light of the calima produces unrepeatable red sunsets and science-fiction landscapes.
Two final clarifications from a local friend. One: the calima brings dust, not sand — the sand on the beaches is marine, not Saharan (card 35); what the calima leaves is a fine film on cars and terraces that the next rain washes away. And two: the episode of February 2020 — the "calima of the century", which closed every airport in the archipelago for a weekend — was exceptional: once in a generation. The normal version is far humbler: a yellow veil, two lazy days and a sunset you will never forget.