Rainfall difference between the periods 2000-2021 and 1950-1999

The graphs show monthly precipitation averages for the periods 2000-2021 and 1950-1999, and their differences, recorded at the meteorological stations of Manresa, Balsareny and Artés in the district of Bages, and Moià in the district of Moianès.

Within the enormous interannual variability of rainfall, the averages that are obtained from a long enough time confirm a slight decrease in rainfall between the second half of the 20th century and the elapsed years 2000-2021 in present 21st century. The highest rainfall lost is in May, August, September, and December; therefore, the decrease is bigger in the second half of the year. Despite the decrease in average rainfall is small, it must be considered that this lower rainfall combines with a wide irregularity and with an unquestionable increase in temperatures. The negative impact on vegetation and crops, and on the flow of springs, rivers and streams, is much more noticeable than what could be understood purely from the small decrease in rainfall averages. To maintain similar soil moisture conditions, a temperature increase of 1ºC should be balanced by an increase in precipitation of at least 30 mm per year.

The table summarizes the annual rainfall averages that are obtained for the two periods and their differences in the 4 weather stations.

Manresa522,0555,3– 33,3
Balsareny575,4599,9– 24,5
Artés533,2573,1– 39,9
Moià620,8679,8– 59,0
Annual rainfall average (mm)

[Data from Servei Meteorològic de Catalunya, graphs Jordi Badia]