According to the meteorological drought index (PDSI) available on IPMA's website, at the end of August, 58.9 percent of mainland Portugal was in a weak drought (a decrease from July (71.4 percent)), 22.6 percent in normal drought, 18 percent in moderate drought and 0.5 percent in severe drought (0.3 percent in July).
According to the index, at the end of August there was still a decrease of the area in weak drought in the North and Centre regions.
In July there had been an increase in the area in meteorological drought in the territory of the continent and, in the regions of Baixo Alentejo and Algarve, an increase in the class of moderate drought, occasionally severe.
At the end of July, 71.4 percent of mainland Portugal was in a weak drought, 19.9 percent in moderate drought, 8.4 percent normal and 0.3 percent in severe drought.
IPMA also advances that the period from January to August 2020 was the hottest of the last 90 years (since 1931).
The institute classifies in nine classes the meteorological index of drought, which varies between "extreme rain" and "extreme drought".
According to IPMA, there are four types of drought: meteorological, agricultural, hydrological and socio-economic.
The meteorological drought is directly linked to the rainfall deficit, when rainfall occurs below what is normal.
Then, as the deficit increases over two, three months, it shifts to an agricultural drought, because there are starting to be water deficiencies in the soil.
If the situation continues, it evolves into a hydrological drought, when there are water shortages in the dams. There is also the socio-economic drought, thus assumed when it already has an impact on the population.
In addition to the drought index, the IPMA Climate Bulletin indicates that the month of August was hot in relation to air temperature and normal in relation to precipitation.
According to the institute, during the month there was a great variability in the values of the air temperature (minimum, average and maximum).
IPMA indicates that in the period from 4 to 10 August there was a heat wave in some places in the North and Centre countryside (Montalegre, Vila Real, Guarda, Penhas Douradas) and temperatures below normal in two periods (12 to 17 and 28 to 31 August).
In these periods the lowest values of the minimum air temperature for the month of August were exceeded in about 10 percent of the meteorological stations on the continent.
With regard to rainfall in August, a value very close to normal (13.9 millimetres) was recorded.
During the month of August, rainfall occurred essentially between 17 and 20 August in the regions north of the Tagus, with very high daily precipitation values for the time, having exceeded the highest values of daily precipitation in some places in the northeast region of the territory.
IPMA also highlights that at the end of August, compared to the previous month, there was a decrease in the percentage of water in the soil throughout the territory, with emphasis on the regions of the Northern Interior, Tagus Valley, Baixo Alentejo and Algarve.