The eighth named storm of the 2020–21 European windstorm season, Filomena formed over the Atlantic Ocean close to the Canary Islands on 7 January, subsequently taking a slow track north-eastwards towards the Iberian Peninsula and then eastwards across the Mediterranean Sea.

Impacts elsewhere were minimal as Filomena moved away from the high to its north, lost its supply of cold air and weakened, and the storm was last noted over Ukraine on 15 January.

[3] The system then moved slowly north-eastwards, crossing the Iberian Peninsula between 8–10 January;[4][5][6] the storm's slow movement contributed to the duration and severity of snowfall across Spain.

After emerging into the Mediterranean Sea, Filomena accelerated eastwards away from the area of high pressure, losing its supply of cold air in the process.

[12] The State Meteorological Agency of Spain (AEMET) named Storm Filomena on 5 January as they issued the first weather warnings ahead of the anticipated severe impact of the system.

[13] Near the coasts, wind gusts of up to 80 km/h (50 mph) occurred as Filomena made landfall on 7 January, as well as 25–50 mm (1–2 in) of rain in southern areas of Spain and Portugal which caused some flash flooding.

In the Sierra Nevada mountains of southern Spain, wind gusts of up to 121 km/h (75 mph) accompanied the large snow totals, leading to blizzard conditions.

[23] The roof of "La Nevera", in the IES Ramiro de Maeztu school, the traditional home of the CB Estudiantes youth system, collapsed due to the weight of snow.

[24] The Military Emergencies Unit (UME) contributed to clear up accesses to hospitals—the event took place amid the third wave of the deadly COVID-19 pandemic and the connected vaccination effort—and the Madrid–Barajas Airport lanes.