[9] The flooding triggered by Numa became the worst weather event Greece had experienced since 1977,[10] and the storm caused an estimated $100 million (2017 USD) in damages in Europe.

Numa II was the stronger of the two, tracking down the centre of the Adriatic Sea, parallel to the Italian coastline and reaching an initial peak intensity of 995 hPa (29.4 inHg) on that day.

[16] Around this time, some computer models forecasted that Numa may soon transition into a warm-core subtropical or tropical cyclone, which would bring stronger winds and more flash flooding to Greece if this were to occur.

Around the time of Numa's peak, the storm had a clear, well-defined eye structure,[8] with the National Oceanic and Atmospheric Administration noting an eyewall similar to that of a hurricane's.

Later on the same day, Numa made landfall in Greece, producing a storm surge at the Gulf of Patras and damaging wind gusts, before rapidly weakening into a low-pressure area afterward.

The fire brigade had received over 600 calls relating to flooding in the days preceding Numa's arrival, dispatching more than 200 firefighters in 55 vehicles to villages across the country to assist.

[24] Numa was linked to exceptionally heavy rainfall across the Balkans in mid-November, which lasted for over week, killing at least 21 people in Greece, with Athens being the worst affected area.

[10][7] Numa began to bring heavy rainfall to already saturated areas of the Balkans beginning on 15 November, causing severe flooding, especially in central mainland Greece.