by EFAS Meteorological Data Collection Centre,

August 2021 was characterized by higher than normal sea surface pressure over the northern Atlantic Ocean and Russia, and close to normal sea surface pressure anywhere else across the EFAS domain. Monthly precipitation totals were above the long-term mean in central and eastern Europe and mainly below in the other parts of the EFAS domain. Monthly mean temperatures were below the long-term mean in northern and central Europe and above over the remaining part of the EFAS domain.

At the beginning of August, the Azores high was around its typical location and an upper-level trough extended from the Artic Ocean via Scandinavia over the Bay of Biscay with weak low-pressure cores at the surface over southern Scandinavia and northeast Russia. Surface pressure gradients in the southern and eastern parts of the EFAS domain were weak and conditions were normal. Within the next days, the trough shifted eastward and a low-pressure system developed over the Baltic Sea. It intensified along its north-eastward track and disappeared reaching the Barents Sea. Another low-pressure system developed over the Atlantic Ocean and moved towards Great Britain and Ireland. It remained active for several days until it disappeared. At the same time, a weak upper-level low-pressure system developed over South-eastern Europe and Anatolia. It is associated with heavy rainfalls at the southern coast of the Black Sea, which caused flash floods. Another low-pressure system developed in the lee of Greenland and it moved north of Great Britain and Ireland to Scandinavia. One more low-pressure system moved along a slightly southward track from the Atlantic Ocean to southern Scandinavia. It caused, forced by orography, heavy precipitation and flash floods at the Alps. Again, a weak upper-level low-pressure system was cut-off and moved to the Black Sea. Another low-pressure system, mainly visible in the upper levels, moved from the Atlantic Ocean via central to eastern Europe. In the next days, the Azores high extended northwards reaching the Norwegian Sea and was later located over Great Britain and Ireland. A low-pressure system developed at the eastern edge of this high-pressure system over northern Scandinavia. It moved slightly southwards, but the associated upper-level trough extended to the western Mediterranean region and caused heavy rainfalls in France and Spain. The low-pressure system moved further to central and eastern Europe and remained active in this region until the end of the month. Another low-pressure system developed over the Atlantic Ocean and arrived at the Iberian Peninsula at the end of August, so it became more prevalent in September.

The highest precipitation totals were observed in the Alps, western Carpathian Mountains, across most of eastern Europe, and in localised areas surrounding Black Sea (Figure 1). No or almost no precipitation fell north of the Caspian Sea, in western Anatolia, over the eastern and southern parts of the Mediterranean Basin (except for the Atlas Mountains), Cyprus, Crete, Sicily, and southern Iberian Peninsula. Monthly precipitation totals above the long-term mean occurred in central and eastern Europe and Scandinavia (excluding southern Norway), central and eastern Anatolia, eastern Atlas Mountains and southeast Iberian Peninsula (Figure 2). Monthly totals below the long-term mean were reported over Iceland, southern Norway, to the north of the Caspian Sea and around the Mediterranean Sea except the above-mentioned regions.

The monthly mean air temperature ranged from -0.5°C to 38.8°C with the highest values in the southern parts of the EFAS domain. The lowest temperature values were reported in the northern and mountainous parts of the domain (Figure 3). Air temperature anomalies ranged from -10.9°C to 9.3°C (Figure 4). Monthly mean air temperature values below the long-term mean occurred in central Europe and in Scandinavia, while positive air temperature anomalies appeared in the remaining part of the EFAS domain.