According to the Portuguese Institute of the Sea and the
Atmosphere (IPMA), a hydrological year is between October 1st and September
30th of the following year and so far, according to IPMA data, the 2021/2022
hydrological year is the second driest since 1931 (since records began), only
surpassed by the hydrological year 2004/2005.
According to an official IPMA source, so far this
hydrological year has had 419 millimetres (mm) of rain, 51% of what would be a
normal value.
With all of mainland Portugal in drought, 55% in severe
drought class and 45% in extreme drought, the IPMA considers that the drought
“would have a significant amelioration” if in the next two months it rained
above average. But it adds that this only happens in 20% of the years.
In average terms, in September in October, for the situation
to improve, something like 150mm in September and 175mm in October.
Although it rained in the spring of this year, in some
regions above average in March, according to preliminary results from the
spring climate report, rainfall in the season corresponded to 80% of normal.
Worsening since last
year
The drought situation of the current hydrological year had
already been worsening since the autumn of last year, when the amount of
precipitation in the months from September to November was 172.8 mm, which
corresponded to about 69% of the average value. Last autumn, according to the
IPMA, was the third driest since 2020. And the month of November was especially
dry, with 90.5 mm less rain compared to the average value.
As a result of an autumn with little rain, the
meteorological drought extended to almost the entire territory at the end of
November and increased in intensity in the south. At the end of autumn, 92% of
the mainland was in meteorological drought, that is, with a lack of rain.
In winter, according to IPMA data, the situation has not
improved, the season was the fifth driest since 1931. The numbers show that the
total precipitation in the months of December to February, 117.6 mm,
corresponded to only 33% of the average value.
January was classified as very dry and February as extremely
dry.
Adding to the lack of rain and high temperatures (the fourth
warmest winter since 1931), last winter saw a worsening of the meteorological
drought, which became more intense across the continent. At the end of winter,
66% of the continent was in the most severe, severe and extreme drought
classes.
Heat waves
In addition to the high temperatures, the country has
already registered two heat waves this year.
Asked by Lusa about whether this worsened the drought
situation, the IPMA source explained that “the hydrological drought that the
mainland faces is directly related to the persistent rainfall deficit recorded
and not so much with the occurrence of heat waves”.
“Heat waves are phenomena that, in some way, are part of the
climatic characterisation of the continental territory and impact the
evaporation of the amount of water stored in reservoirs, dams and dams”, they
added.