According to the Portuguese Institute of the Sea and the Atmosphere (IPMA), data from the latest bulletin available on the IPMA website indicate that the weak drought that ended the region of Minho and Douro Litoral ended in late November. At the end of December, 50.4 percent of the territory was in a situation of light rain, 49.1 percent normal and 0.5 percent in moderate rain. According to the previous report, at the end of November, 62.3 percent of the territory was in a situation of light rain, 33.6 percent in normal and 4.1 percent in weak drought.
The institute classifies the drought meteorological index into nine classes, which varies between “extreme rain” and “extreme drought”. According to the IPMA, there are four types of drought: meteorological, agricultural, hydrological and socio-economic. Meteorological drought is directly linked to the deficit of precipitation.
In addition to thedrought index, the Bulletin indicates that the month of December in mainland Portugal was classified as cold in relation to air temperature and normal in terms of precipitation. The mean value of the average air temperature (9.75 degrees Celsius) was lower than normal with an anomaly of -0.21 degrees.
According to the IPMA, the average value of the minimum air temperature (5.85 degrees Celsius) was 0.20 degrees lower than the normal value and the average value of the maximum (13.66 degrees) was also lower than normal, with an anomaly of - 0.23 degrees. The lowest value of the minimum temperature was recorded on the 27th in Carrazeda de Ansiães, Bragança (-5.2 degrees) and the highest value in Aljezur, in Faro, on the 1st (23.6 degrees).
With regard to precipitation, the average value of the quantity in December, 123.8 mm (mm), corresponds to 86 percent of the normal value 1971-2000. “During the month, the period from 9 to 20 December should be highlighted with the occurrence of high values of accumulated precipitation in 24 hours in almost the entire territory, but especially in the northwest region (daily values greater than 90.0 mm)”, according to the bulletin.
At the end of December, there was a general increase in the territory of the values of percentage of water in the soil with most of the North and Central regions with values very close to or even equal to capacity. The lowest values of percentage of water in the soil (less than 60 percent) were found in the Baixo Alentejo region.