Another explanation

It turns out that there are actually 15 months in Paris instead of the usual 12. In English, they are:
January
February
March
April
May
June
July
August
September
October
November
November
November
November
December

Note: this joke was originally about Vienna, but boy does it apply here. Note to self: Juliette says that the worst months are November and February to early March (to compensate for February being so short and all).