Hellenion’s December 2018 Festival calendar,
from https://www.hellenion.org/calendar/
Maimakterion – Poseideon
Year 2 of the 699th Olympiad
7 Dark of the moon
8 Libation to Dionysos; Hekate’s Deipnon
9 Noumenia
10 Agathos Daimon
16 Poseidea
18 Country Dionysia (?)
21 Heliogenna; Solstice
22 Heliogenna; Full moon
31 New Year’s Eve