Why do riads feel humid, especially at night?
The short answer
Courtyard fountains, thick earth walls that retain moisture, and limited air exchange between enclosed rooms create higher relative humidity indoors. At night, temperature drops cause condensation on cool wall surfaces.
The sheets feel damp. Not wet — just heavier than they should be. The towel you hung at noon is still not dry by evening. The air in your room has a weight to it that wasn't there during the day.
The courtyard fountain that cools the riad during the day is still running at night. Evaporating water adds moisture to the air continuously. The orange trees are still transpiring. The earth walls — pisé and tadelakt — are porous by design, absorbing and releasing moisture as humidity shifts. During the day, when hot dry air dominates, the walls absorb moisture. At night, when temperatures drop and relative humidity climbs, the walls release it.
The architecture that keeps you cool creates this. Thick walls and small openings mean limited air exchange with the outside. The courtyard that functions as a cooling chimney during the day becomes a moisture trap at night, when the convection loop weakens and humid air settles into ground-floor rooms.
This is not a design flaw. It's the other side of the same system. Riad architecture trades humidity management for temperature management — a reasonable deal when daytime temperatures exceed forty-five degrees. Modern riads with mechanical ventilation handle both. Older ones make you choose. Most guests, discovering the alternative is a room at forty-four degrees, choose the damp towel.