Damp, humidity, and the number IPMA stopped publishing

What is actually measured, and what is not

IPMA's current climate normals sheet for Funchal, covering 1991 to 2020, publishes air temperature and precipitation. It publishes no humidity of any kind. That sheet was opened for this page and checked line by line; the variable is simply absent from the current series.

The previous series does carry it. The 1971 to 2000 normals sheet for Funchal/Madeira, station 522, at an altitude of 58 m*, source: IPMA, read August 26, 2026, gives a mean relative humidity of 72%*, source: IPMA / Instituto de Meteorologia, 1971-2000 normal period, read August 26, 2026, and the monthly values run from 69%*, source: IPMA / Instituto de Meteorologia, 1971-2000 normal period, read August 26, 2026 in April to 74%*, source: IPMA / Instituto de Meteorologia, 1971-2000 normal period, read August 26, 2026 in January, February, July and December.

Three caveats that matter more than the number

• It is measured at a single moment each day, 09h UTC, not averaged across twenty-four hours. Relative humidity swings enormously between dawn and mid-afternoon, so a single morning reading is not a description of a day.
• The underlying data runs from 1971 to 1999. It describes a period ending more than twenty-five years ago.
• It is Funchal. Station 522 sits on the sheltered south coast, near sea level, in the driest populated part of the island.

For the north coast and the mountains there is nothing. IPMA publishes standalone normals fact sheets for only two stations in the whole archipelago, Funchal and Porto Santo, and neither the current series nor the monthly Madeira climate bulletins report relative humidity for Santana, Chão do Areeiro, Ponta de São Jorge or anywhere else. A relative-humidity figure for the north coast of Madeira does not exist in the official record. Any page that quotes one has taken it from a model, from a weather app, or from nowhere.

The measurement that does exist, and what it shows

What IPMA does publish for the north and the high ground is rainfall, and it publishes it in a form that settles the argument. Its Madeira climate bulletin reports accumulated precipitation for the hydrological year across four reference stations at once, so the comparison is like for like.

From 1 October 2025 to 31 July 2026, the same ten months at each station:

• Funchal/Observatório, on the south coast: 599.0 mm*, source: IPMA, hydrological year 2025/2026 to 31 July 2026, read August 26, 2026
• Santana, on the north coast: 1,125.5 mm*, source: IPMA, hydrological year 2025/2026 to 31 July 2026, read August 26, 2026
• Chão do Areeiro, on the central plateau: 2,562.4 mm*, source: IPMA, hydrological year 2025/2026 to 31 July 2026, read August 26, 2026
• Porto Santo: 537.1 mm*, source: IPMA, hydrological year 2025/2026 to 31 July 2026, read August 26, 2026

The plateau took more than four times Funchal's rainfall over the identical period. The north coast took close to twice it. These are not modelled estimates or averages of averages; they are one instrument's accumulated total against another's, printed side by side in the same document.

The wind explains why

IPMA's wind roses for the same month show the mean wind arriving predominantly from the northern quadrant, with a sharply defined north-easterly component at Chão do Areeiro. Moist Atlantic air arrives on the north side, is forced up over the ridge, cools, and drops its water on the way. What reaches the south coast has already been wrung out. That is the entire mechanism, and it is why the north looks the way it does in the photographs.

For context on the south side, the long-run Funchal normal is 574.3 mm*, source: IPMA, 1991-2020 normal period, read August 26, 2026 a year, falling on 53.4 days*, source: IPMA, 1991-2020 normal period, read August 26, 2026. Funchal is a dry place by any European standard. It is also, on the same instrument, a place with a mean morning humidity just under three-quarters. Both things are true, and the tension between them is the whole subject.

Why aspect and altitude decide it, not the island

Condensation forms where air meets a surface colder than its dew point. That is a statement about surfaces, not about a climate, and it is the reason two houses on the same street behave differently.

Three variables drive it: how cold the wall gets, how much water is in the air touching it, and how much of that air is exchanged for drier air. Madeira loads the dice on all three in particular places.

Aspect

A north-facing wall on this island receives no direct winter sun. Its outer face stays cold, its inner face stays cold, and every warm humid airmass that touches it gives up water. The same wall facing south gets heated for hours a day and dries between events. This is ordinary building physics rather than anything Madeiran, but the island's relief makes aspect unusually decisive: a valley wall can put a house in shadow for most of a winter day even on the south coast.

Altitude

Height does two things at once. It lowers the temperature, and on this island it also raises the rainfall — the plateau figure above is the measurement of that. A house above the usual cloud base spends part of the year inside cloud rather than under it, which is a different exposure from rain. IPMA's own bulletins name fog on the plateau; the regional tourism service states plainly that fog and cooler temperatures are common in the mountains while it is sunny and warm at the sea.

How different those two places are

Funchal's observatory recorded a mean of 0.3 days*, source: IPMA / Instituto de Meteorologia, 1971-2000 normal period, read August 26, 2026 across the 1971 to 2000 series, roughly one foggy day every three years at that station. The same island's plateau is known for cloud that sits on the ground. The distance between those two facts is about twenty minutes by road, and it is the single most important thing to understand before choosing between the coasts and the altitudes on offer.

What shows up in a viewing

This is where the subject stops being climate and becomes a property matter, which is why it belongs alongside how a purchase here actually runs rather than in a weather page.

The signals are the ordinary ones and none of them needs equipment: staining low down on a wall and at the junction of wall and ceiling; marks behind furniture standing against an external wall; blistered or lifting paint; salt deposits on plaster; a bloom in the corners of a cool room; and the smell that returns when a closed-up room is opened.

The smell is the most reliable of them, for an unglamorous reason: it is the hardest thing to remove for the length of a viewing. Staining can be painted, furniture can be moved, and a house can be aired for a morning. A room that has been shut for a fortnight tells the truth in about four seconds.

The question that separates a defect from a climate

Damp on a north-facing wall in a high village is not necessarily a fault in the building. It may be the building performing normally in a place where the air is wetter and the wall is colder. The distinction that matters is whether water is arriving from outside through a failure, a roof, a gutter, a crack, ground water rising into a wall without a barrier, or condensing on the inside out of the air in the room. Those have different causes, different costs and different consequences for a price.

No Madeira-specific published figures were found for the cost of remedying either, for the prevalence of either in the housing stock, or for any regional building requirement addressing them. Those numbers are not given here because they were not found, and inventing them would be worse than leaving the gap visible.

What can honestly be said about mitigation

The physics allows only three levers, and every product sold on this island is one of them wearing a different name: warm the surface, remove water from the air, or exchange the air.

Heating raises wall temperature above the dew point. Dehumidification removes water directly. Ventilation replaces humid indoor air with drier outdoor air, which works when the outdoor air is drier, and which is precisely the assumption that fails on a wet north-coast morning in February. That last point is the one most general advice written for northern Europe gets wrong when it is applied here.

What none of these do is fix water arriving through a fabric failure. A dehumidifier running against a leaking gutter is an electricity bill, and electricity here is not cheap — the published rates are set out in what living on the island actually costs.

The seasonal pattern is worth reading alongside what each month actually looks like: the rain concentrates from October through March, and those are the same months in which a wall gets least sun. The two effects arrive together rather than taking turns.