The MOYENNE.SI.ENS (AVERAGEIFS) function calculates the average of the values of a range for the rows that meet several criteria. It returns #DIV/0! if no row matches, which is handled with SIERREUR. Like SOMME.SI.ENS, it takes the range to average first.
Example
=MOYENNE.SI.ENS(C2:C100;A2:A100;"Nord")