Spain. The summer of 2026 was the hottest measured in Spain since official records began in 1961. The Spanish Meteorological Agency (AEMET) recorded a record 61 days of heat wave in the peninsula and the Balearic Islands. Temperatures reached 44.2°C in Murcia and 42.8°C in Seville. In the five museums surveyed by The Arts Journalthe equipment held up. No unusual increases in rooms, major breakdowns or damage to collections have been reported. But behind the scenes, the heat increased the demand on the machines and the surveillance of the teams.
The Seville Museum of Fine Arts offers the most exposed case. Installed in a former convent, it alternates air-conditioned galleries and open patios. “Air conditioning is designed not only for users and employees, but above all according to collections”, underlines Ignacio Hermoso Romero, curator and head of the conservation and research department. It therefore operates continuously, museum open or closed. Controlled by computer and sized for the most extreme conditions of the Sevillian climate, it did not require any extraordinary intervention this summer.
In the patios which punctuate the visit, however, the heat remains noticeable. The museum relies on solutions proven for centuries in Andalusian architecture. Fountains, vegetation and shade cloths refresh the atmosphere. The historic character of the former convent has required the installation of air conditioning and will also affect the planned extension in a neighboring building. Thanks to its interior conditions and its wide opening hours, the establishment also plans to be able to serve as a climatic refuge.
At the Prado, the rooms did not overheat either, but the cold production had to increase. When outside temperatures remain exceptionally high for several days, the museum puts more of its four refrigeration units into operation. The redundancy of the equipment allows it to maintain the spaces housing works between 21 and 23°C. “So far, no incidence has compromised the environmental conditions required for the conservation of the works,” explains Eva Cardedal, head of the facilities department.
Humidity, a major challenge for Mediterranean museums
On the Catalan coast, maritime humidity further complicates cooling. Beneath the galleries of the Museu Nacional d’Art de Catalunya (MNAC), kilometers of pipes run through the bowels of the Palau Nacional. From 5 a.m., a technician examines the external conditions and adapts the temperature of the water sent into the network. Some 200 air handling units watch over this building built for the 1929 International Exhibition.
The National Art Museum of Catalonia in Barcelona.
Maintaining around 25°C and 55% humidity in summer requires, according to Xavier Abelló, MNAC infrastructure manager, “around two and a half times more cooling capacity than the Prado”. The dry air of Madrid can be directly cooled. The one in Barcelona must first be lowered to the dew point in order to extract the water, before being reheated. Some aging machines have been replaced, sometimes urgently. “The works have never had to suffer. We have always moved heaven and earth to compensate for possible shortages of refrigeration power”assures Xavier Abelló. He nevertheless questions the future capacity of installations designed according to climate hypotheses that are now outdated.
Glass poses another challenge for MACBA. Facing south, the building designed by Richard Meier is crossed by a vast glass atrium where heat accumulates. “We had to adapt the Meier building to the climatic requirements of a museum”summarizes Alberto Santos, head of general services. The galleries were gradually isolated from the atrium and corridors in order to better control their temperature.
During the summer, the MACBA slightly raised the indoor temperature, while remaining within the limits set for the collections. This measure also lowered the relative humidity. The reserves have an independent system and autonomous dehumidifiers. Maintenance and security check the probes daily, while sensors alert teams on their phones of the slightest deviation. Because, “above 25°C and 60 to 65% relative humidity, there is a risk of development of micro-organisms”, explains Silvia Noguer, head of conservation-restoration at MACBA.
Renovate to resist heatwaves
In seven years, the museum has renewed its entire cold water production. He is now preparing the replacement of around 500 m² of glazing and wishes to separate the air conditioning of the rooms from that of the atrium. Cross ventilation would allow hot air to be evacuated. “We produce cold to compensate for a permanent supply of heat coming from outside”observes Alberto Santos. Opposite the museum, the Documentation Center has belonged since 2023 to the Barcelona network of climate refuges. Free and accessible directly from the street, it welcomed 1,558 people between June and August 2026, compared to 1,091 during the same months of 2025.
Bilbao’s oceanic climate is less scorching, but also humid. In summer, the Guggenheim places the thermostat in the upper part of its temperature range in order to reduce the effort required of the installations. “External conditions tell us which side of the range to place to minimize energy consumption”explains Rogelio Díez, deputy director of maintenance and facilities. Aitziber Velasco, conservation technician, confirms that this management has not resulted in “no change or deterioration of the works”.
The heatwave has therefore not reached the galleries, but it is already weighing on their operations. Machines are put to greater use, humidity control is becoming more complex and thermal weaknesses in buildings must be corrected. This apparent comfort depends on installations active day and night, constant maintenance and teams capable of reacting before visitors or works feel the effects of the heat.
