The first snow of the season in central-southern Italy is occurring these days, with snow also in unusual places.
However, December has not seen any relevant episode, except before Christmas, when some snow fell in the Po valley (especially in Emilia Romagna).
I have extracted data from the main cities in Italy and plotted the results in order to have a general overview of the maximum and minimum temperatures observed in December and compared with the long-term average 1971-2000 (there is no data for Aosta in N.W. Italy).
Regarding the average maximum and minimum temperatures observed during the last month (Figure1), we can see how the highest temperatures are observed in the south (mainly Sicily and Sardegna) with average temperatures between 14-16 °C. Instead, in the north, except for Liguria, the maximum values were below 10 °C on average.
Regarding the average minimum temperatures, only in few cities (regions) the values are below 0°C, with Bolzano the coldest one.
Considering now the comparison of the observed temperatures with the climatological average (1971-2000), we can see how southern Italy (mainly the regions along the Adriatic coast) have observed negative anomalies in both the minimum and maximum values (Figure2). Instead, in N.W. Italy the most significant positive anomalies are observed especially in the maximum values (more than +2 °C in Lombardia), instead in N.E. Italy the anomaly is less (between +0.5/ +1 °C).
The positive anomalies in N.W. Italy are mainly due to the frequent episodes of fohn, caused by a strong flow of northerly winds towards the Alpine region, which have caused sunny and dry conditions in the southern part of the Alps and mild temperatures (the last episode occurred few days ago). Instead, in southern Italy more rainfall and overcast conditions (as well as the easterly winds) have contribute to the (little) negative anomalies.