dnd 5e – D&D Wiki, Orizon Setting: What is the last month on the calander?

So I have found an awesome campaign setting on D&D wiki but its missing some info.

The calendar has every month named except for one, I have all the others but if someone can tell me the last one that would be awesome thanks.

Here is what I have so far

14 months

1: Lencten
2: Errach
3: Haru
4: Lithe
5: Sumor
6: Samrad
7: Natrisu
8: Thout
9: Fogamur
10: Haerfest
11: Gemred
12: Yule
13: Frosyu