May started off cool. During the first few weeks, temperatures in Spain were below normal across almost the entire country. Nothing hinted at what was to come. Since 19 May, however, the thermometers have been climbing steadily, reaching values that, under normal conditions, belong in the height of summer.
The culprit is a high-pressure system stretching from North Africa to the British Isles, which meteorologists call an anticyclonic ridge or, in more popular terms, a heat dome.
The mechanism is simple: this high-pressure system acts like a lid that prevents the air from renewing, forces it to sink and, as it is compressed, heats it up even more. The result is a stifling atmosphere that does not let up for days and which, in some places, represents an anomaly of up to 15°C above the usual values for this time of year. In other words: the kind of heat normally expected in July or August has arrived two months early.
Spain's meteorological agency AEMET points out that at Santander airport, where records go back to 1954, temperatures above 30°C had only been recorded on two days before June. This year there have already been six. At the Badajoz Airport observatory, with 71 years of data, temperatures above 38°C have been recorded in May for the first time in the entire series.
