You wake up, the light through the shutters is wrong, and the sky has gone the colour of weak tea. The car outside is coated in something reddish. By afternoon it is on the terrace, on the window sills, on the outdoor table, and on the white railings that you washed on Friday.
That is calima, and if you have owned a home in the Eastern Algarve for more than a couple of years you have already lost a weekend to it. What most people do next is the natural thing and also the wrong thing: they take a dry cloth or a broom to it.
This guide explains what the dust actually is, why the obvious method makes it worse, and how to clean it off properly, surface by surface. It also covers the part nobody thinks about until it is too late, which is what the dust does to the inside of a house that was left with the windows open.
What calima actually is
Calima is the common name for an intrusion of mineral dust carried up from the Sahara and North Africa and transported north on high altitude winds. It reaches Portugal regularly, often arriving first at Madeira and the Canaries before continuing to the mainland.
Visually it is unmistakable. The sky turns whitish or yellowish during the day, sunsets go deep orange, visibility drops, and everything exposed collects a film of dust. The particles include the fine fractions measured as PM10 and PM2.5, and the plume can carry pollen, fungi, bacteria and other microorganisms along with the mineral content.
It is not a freak event, and it is becoming less freakish. One study comparing the periods 2003 to 2019 and 2020 to 2022 found a very significant increase in the frequency of Saharan dust intrusions over Europe, with recent episodes running around eight times more frequent than previously, including during winter months. Episodes are common in winter and early spring, which surprises people who assume this is a summer phenomenon.
Is it a health problem?
For most healthy adults an episode is an inconvenience rather than a hazard, but Portuguese health authorities do issue guidance and it is worth following if it applies to you.
During episodes, concentrations of PM10 and PM2.5 rise, and those are the particles associated with aggravating asthma, bronchitis, chronic obstructive pulmonary disease and cardiovascular problems. The Direção-Geral da Saúde advises that children, the elderly and people with respiratory or cardiovascular conditions stay indoors where possible, keep windows closed, avoid physical exertion and outdoor activity, and that chronic patients maintain their usual medication. If symptoms worsen, the guidance is to contact SNS 24 on 808 24 24 24.
The practical version for a household: close the windows early rather than late, and do the outdoor cleaning after the episode has passed rather than during it. Cleaning a terrace in the middle of a dust event is both futile and the worst moment to be breathing hard outdoors.
Why dry dusting makes it worse
This is the single most useful thing on this page.
Saharan dust is extremely fine and mineral, which means the particles are hard and slightly abrasive. Three things follow.
A dry cloth does not lift it, it drags it. On glass and on painted surfaces that produces streaks that are visibly worse than the dust was. On a car, and on polished or lacquered surfaces indoors, dragging abrasive mineral particles across the finish is how you get fine scratching.
A broom on a terrace lifts the dust back into the air, where a good proportion of it settles again within the hour, frequently onto the furniture you have just wiped. And on fabric, brushing pushes the particles deeper into the weave instead of removing them, which is why beaten cushions often look worse afterwards.
The rule for calima is simple: water first, cloth second. Anything dry is either moving the problem or grinding it in.
The right order, and why order matters
Sequence is what separates a job that takes an hour from a job you do twice.
Work from the top down and from the inside out. Railings and balustrades before tables. Tables before chairs. All of it before the floor. And every outdoor surface before you touch the glass that faces it, because washing a terrace throws a fine spray of dust laden water onto any door or window nearby, and the glass you cleaned first will need doing again.
- Wait until the episode has passed. Cleaning mid event is wasted work.
- Rinse high fixed surfaces: railings, balustrades, wall lights, awning frames.
- Wash outdoor furniture with water and a mild detergent, rinsing rather than wiping dry first.
- Deal with cushions and fabrics separately, see below.
- Hose or mop the terrace floor, working toward the drain.
- Only now clean the glass, frames and sills.
- Finish with shutters and their slats, which hold more dust than any other exterior element.
Surface by surface
| Surface | Do | Do not |
|---|---|---|
| Glass and windows | Rinse first, then clean wet with a squeegee or damp microfibre | Spray glass cleaner onto dry dust and wipe. It smears every time |
| Terrace floor | Hose down, or mop with plenty of water changed often | Sweep dry. It relocates the dust rather than removing it |
| Outdoor cushions | Vacuum first if you can, then wash covers after a heavy episode | Beat or brush them. It drives particles into the fabric |
| Painted railings | Rinse, then wash with mild detergent | Dry wipe. Fine mineral grit plus pressure equals marking |
| Shutters and blinds | Damp cloth, slat by slat, rinsed frequently | Feather duster. It aerosolises the dust indoors |
| Cars | Rinse thoroughly before any contact | Wipe with a dry cloth. This is how paintwork gets scratched |
| Solar panels | Rinse with clean water once the episode ends | Leave it. Deposition measurably reduces panel efficiency |
| Pool surrounds | Wash away from the pool, check the filter afterwards | Hose it toward the water and then wonder why the filter clogs |
The solar panel line is worth expanding, because it is the cost people never attribute to calima. Dust deposition reduces the efficiency of solar panels, and in a region with as many installations as this one, an unwashed array after a heavy episode is quietly costing money for weeks.
Indoors: the part nobody plans for
If the windows were open when the dust arrived, and in an Algarve summer they usually were, you now have a fine mineral film on horizontal surfaces throughout the house. It is subtle enough that people often do not register it as dust at all, and instead notice that surfaces feel slightly gritty.
Indoors the same rule applies. Damp microfibre, not dry cloths, not feather dusters, and not a vacuum without a decent filter, because a poor filter simply redistributes fine particles into the air of the room you are standing in.
The places it collects that people miss: the tops of door frames, curtain rails, the upper edge of skirting boards, inside the tracks of sliding doors, and the mesh of insect screens, which act as a very efficient dust trap and then release it back into the room every time a breeze comes through. Screens are worth rinsing outdoors rather than wiping in place.
If you have a holiday rental
Calima has a particular way of costing money in a rental, and it is not the cleaning time.
Properties here are let on their outdoor space. A guest arriving at four o’clock at a property whose photographs show a bright terrace, and finding a table and cushions covered in reddish film, reads it as a property that was not cleaned. That perception does not distinguish between dust that arrived on Wednesday and dust that arrived twenty minutes before check-in.
Two practical measures. First, check the forecast for dust intrusions the same way you would check for rain, and build an outdoor pass into the changeover on those weeks even where it is not usually included. Second, store cushions inside between bookings during the dust seasons, which costs nothing and removes the worst of the problem.
If a heavy episode has landed and you have guests arriving, this is precisely the situation a one off deep clean exists for, and terraces washed free of calima dust are part of what that covers here.
What to do while an episode is happening
Short list, because most of it is about not making work for yourself later.
- Close windows and shutters, particularly on the side the wind is coming from.
- Bring cushions and soft furnishings indoors if you can reach them without spending twenty minutes outside.
- Cover or move anything with a delicate finish that lives on the terrace.
- Postpone laundry that would otherwise dry outside. Line dried sheets during a dust episode come in worse than they went out.
- Do not wash the car, and do not wash the terrace. Both will need doing again.
- Run air conditioning on recirculation rather than fresh air intake where that option exists.
After the episode: the twenty minute version
If you do not have a full morning, this is the order that removes most of the visible problem in about twenty minutes for a typical apartment terrace.
Hose the railings and the floor. Wipe the table and chairs with a wet cloth, rinsing it repeatedly rather than trying to make one pass do everything. Clean the glass wet, last. Leave the shutters and the insect screens for when you have longer, since they are the slowest element and the least visible to anybody who is not looking for them.
Then check two things people forget: the drain on the terrace, which collects the washed off dust as a fine silt, and the pool filter if you have one.
When it is worth calling somebody
A single episode on an apartment terrace is a domestic job. Three situations are not.
A property that has stood closed through a series of episodes, where the film has built up over months rather than days and has combined with salt air and winter humidity. A villa with extensive outdoor space, awnings, multiple sets of shutters and a pool surround, where the job is measured in half days rather than hours. And any property with guests arriving where the outdoor space is central to the booking.
We wash terraces and outdoor furniture free of calima dust as part of deep cleans across Tavira, Cabanas, Santa Luzia and the rural areas around Santo Estêvão and Luz de Tavira. If it is a recurring problem rather than a one off, folding an outdoor pass into regular cleaning during the dust seasons costs far less than repeated emergency cleans, and you can see what we cover on the areas page.
Frequently asked questions
What is calima, exactly?
It is the common name for an intrusion of mineral dust from the Sahara and North Africa, carried north on high altitude winds. In Portugal it typically shows as a yellowish or whitish sky, reduced visibility, orange sunsets, and a fine reddish film on every outdoor surface. It often reaches Madeira and the Canaries first before affecting the mainland.
Is Saharan dust dangerous?
For most healthy adults it is an inconvenience. Concentrations of PM10 and PM2.5 rise during episodes, and health authorities advise that children, the elderly and people with respiratory or cardiovascular conditions stay indoors where possible, keep windows closed and avoid outdoor exertion. Chronic patients should maintain their usual medication and contact SNS 24 if symptoms worsen.
Why does my glass streak when I clean off dust?
Because the dust is fine and mineral, and a dry or barely damp cloth drags the particles across the glass rather than lifting them. Rinse the glass with water first, then clean it wet. The same principle explains why dry wiping a dusty car risks scratching the paint.
When is calima season in the Algarve?
Episodes are frequent in winter and early spring, driven by strong winds and particular atmospheric patterns, but they occur through the year and have become considerably more frequent over the last few years. Treating it as a summer only phenomenon is why people are caught out in February.
Does the dust affect solar panels?
Yes. Deposition on the panel surface reduces efficiency, so a rinse with clean water after a heavy episode is worth doing rather than waiting for the next rain, which may itself arrive carrying more dust.
