63°C in Valencia, Spain: real temperature or heat index?

63°C in Valencia: real temperature or an invention of the heat index?

A blunt claim: the 63°C published by Las Provincias is the real temperature reached on Valencia's asphalt, not a heat index. The official method, measuring in the shade at 1.5 metres, understates the heat people endure on the street. But meteorologists counter that this is not the correct way to measure air temperature, and that doing so in the sun would produce absurd readings.

The scientific method versus citizen perception

Official temperature measurement is carried out with precision thermometers installed in ventilated shelters, in the shade and at a regulated height of 1.5 metres. The goal is to measure air temperature, not the sun's direct radiation on a surface. As an engineer taking part in the debate explains, radiant temperature can vary by up to 40°C within a single hectare depending on the material (sand, asphalt, grass). Moreover, when a cloud passes, the temperature drops instantly: it is not a reliable indicator.

Those who defend the 63°C figure argue that this is the temperature a pedestrian actually feels in the sun, and that the official reading does not reflect the real danger. The debate includes extreme examples: in Death Valley (California), 57.6°C was recorded in the shade in 1918, and 54.4°C in 2020. Valencia, with its humid climate, has never exceeded 46°C officially. The 63°C figure is, according to sceptics, a sensationalist hook.

The controversy over the "heat index"

The Las Provincias article was headlined with 63°C, but was corrected or qualified as a heat index. However, a current of opinion holds that the heat index is, in fact, the real temperature acting on the body, and that official data are irrelevant to everyday life. It is compared with measuring a person's temperature instead of the air's: if you want to know whether it is hot on the street, measure on the street, not in a hut.

On the other hand, defenders of the standard method point out that radiant temperature is fickle and that a thermometer exposed to the sun heats up on its own, giving values that do not correspond to the ambient conditions. Furthermore, infrastructure such as railway tracks does not deform because of air heat, but because of radiation on the materials, a different problem.

Implications for the climate debate

The discussion goes beyond meteorology. Underlying it is distrust of official institutions (AEMET, the media) and criticism of how extreme events are communicated. For some, the 63°C is proof that the severity of warming is being hidden; for others, it is a hoax that spreads antiestéticar without scientific basis.

The curious fact: as one user points out, fish cooks at 65°C with a probe. So in Valencia, theoretically, you could cook sea bass in the sun on the windowsill. An irony that illustrates just how unreal the figure seems.

Where are we heading?

The controversy will not be settled with technical arguments, because it is a dispute between two ways of seeing reality: that of the scientific standard (air in the shade) and that of direct experience (what burns to the touch). With every heatwave, the debate flares up again. And as long as there is no consensus on what to measure and how to report it, headlines like Las Provincias' will keep feeding distrust. The predictable outcome is that the next heatwaves will bring new heat index figures that clash with official records, and that scepticism towards public data will only grow.