According to a report from the Portuguese Institute of the Sea and the Atmosphere (IPMA), Mora and Alvega (Abrantes) surpassed the previous absolute extreme for May, the 40ºC recorded in Pinhão on 30 May 1953, and in Termas de Monfortinho during the last two days of May 2001.
With data updated this morning, the IPMA says that 16 automatic weather stations are experiencing a heat wave.
Although the hot period affects the entire continent, the heat wave began on 20 May and is occurring in the Alentejo and Tagus Valley regions. In the central region and on the coast, the Anadia station also entered a heat wave, according to IPMA information.
In terms of the number of days, this heatwave is the eighth-longest, at 7.9 days. The longest was in 1964, at 9.7 days. Regarding magnitude, this episode is the third largest.
According to IPMA (Portuguese Institute of the Sea and the Atmosphere), 22 new maximum air temperatures have been recorded so far, one on Tuesday and the others on Wednesday. Four new maximum and minimum air temperatures were also recorded.
IPMA warns of the high probability of more locations entering a heatwave, especially in the northern and central interior regions, and says there is also a strong probability that the current heatwave will extend into the first days of June.
A heatwave occurs when, over at least 6 consecutive days, the daily maximum temperature is 5°C above the average daily maximum for the respective month.
A reference period is used for comparison purposes; currently, the period 1991-2020.
The Portuguese Institute for the Sea and the Atmosphere (IPMA) says that heat waves can occur at any time of year, but their impact is most noticeable in the summer.
Heat waves have occurred since the 1940s (when more data began to be available), but in the last 30 years, more cases of extreme heat waves have been observed in the summer on the mainland. The northern and central interior and the Alentejo region are the most affected.