Greyhawk Calendar

The specific month and date in-game is different between games. For the the Thieves Guild campaign, the date is always the rough real-world equivalent.
Holidays: Needfest 1 – New Year’s Day (holy to Celestian)
Needfest 4 – Luna new (holy to Nerull)
Needfest 4 - Celene full (holy to Olidammara)
Needfest 4 - Holy to Istus and Wee Jas
Needfest 7 – Holy to Hieroneous and Vatun
Fireseek 1 – Holy to Vecna
Fireseek 11 – Luna full (holy to Olidammara)
Fireseek 14 – Holy to Hextor
Fireseek 18-20 – Luna Morta (holy to Boccob)
Fireseek 25 – Luna new (holy to Nerull)
Readying 1 – Festival of St. Bane
Readying 2 – Holy to Pelor
Readying 4 – Holy to Zilchus
Readying 6 – Holy to Kord
Readying 7 – Holy to Kurell
Readying 8-14 – Rising Fest (holy to Beory)
Readying 11 – Luna full (holy to Olidammara)
Readying 15 – Celene new (holy to Lendor)
Readying 24 – Day of Lords (holy to Zuoken)
Readying 25 – Luna new (holy to Nerull)
Coldeven 2 – Holy to Al’Akbar
Coldeven 5 – Holy to Velnius
Coldeven 11 – Luna full (holy to Olidammara)
Coldeven 11 – Fullmoon Festival (holy to Pholtus)
Coldeven 14 – Holy to Phaulkon
Coldeven 20 – Holy to Bralm
Coldeven 25 – Luna new (holy to Nerull)
Coldeven 26 – Holy to Hieroneous
Growfest 1 – Banapas
Growfest 2 – Holy to Lydia
Growfest 4 – Holy to Merikka
Growfest 6 – Atroa’s Feast (holy to Atroa)
Growfest 7 – Fool’s Day (holy t Ye’Cind)
Planting 1 – Holy to Syrul
Planting 2 – Holy to Pelor
Planting 4 – Luna full (holy to Olidammara)
Planting 4 – Courting Moon Festival (holy to Ehlonna)
Planting 5 – Holy to Osprem
Planting 7 – Holy to Mouqol
Planting 11 – Tanabat
Planting 18 – Luna new (holy to Nerull)
Planting 20 – Holy to Berei
Planting 24-25 – Holy to Llerg
Flocktime 2 – Holy to Joramy
Flocktime 4 – Luna full (Holy to Olidammara)
Flocktime 4 – Holy to Phyton
Flocktime 8-14 – Ulaa’s Hunt
Flocktime 8-14 – Harnekiah
Flocktime 15 – Vernal Equinox (holy to St. Cuthbert and the Old Faith)
Flocktime 15 – Celene full (holy to Wee Jas)
Flocktime 18 – Walpurgis
Flocktime 18 – Luna new (holy to Nerull)
Flocktime 22-28 – Holy to Fortubo
Wealsun 1-7 – Festival of Blinding Light (holy to Pholtus)
Wealsun 1 – Goodrhys
Wealsun 4 – Luna full (holy to Olidammara)
Wealsun 10-11 – Luna Discorda (holy to Boccob)
Wealsun 10 – Holy to Zagyg
Wealsun 11 – Holy to Norebo
Wealsun 13 – Holy to Bleredd
Wealsun 14 – Holy to Phaulkon
Wealsun 16 – Bawming the Thorn (holy to Sotillion)
Wealsun 17 – Ceremony of the Turning
Wealsun 18 – Luna new (holy to Nerull)
Wealsun 27 – Holy to Jascar
Wealsun 28 – Holy to Beltar
Richfest 1-7 – Holy to the Old Faith
Richfest 3 – Holy to Hieroneous
Richfest 4 – Midsummer’s Day (holy to Pelor)
Richfest 4 – Luna full (holy to Olidammara)
Richfest 4 – Celene full (holy to Wee Jas and Mayaheine)
Richfest 5 – Holy to Xerbo
Richfest 6 – Holy to Fharlanghn
Richfest 7 – Holy to Myrhiss
Reaping 2 – Holy to Pelor
Reaping 7 – Holy to Rudd
Reaping 11 – Luna new (holy to Nerull)
Reaping 12 – Holy to Allitur
Reaping 18-20 – Luna Vita (holy to Boccob)
Reaping 19 – Holy to Procan
Reaping 20 – Holy to Ulaa
Reaping 25 – Luna full (holy to Olidammara)
Reaping 25 – Holy to Incabulos
Goodmonth 2 – Feast of Frogs (holy to Wastri)
Goodmonth 4 – Grandmote (holy to Lirr)
Goodmonth 5-9 – King’s Festival
Goodmonth 7 – Pater Larch (holy to Geshtai)
Goodmonth 11 – Luna new (holy to Nerull)
Goodmonth 15 – Holy to Pyremius
Goodmonth 23 – Holy to Erythnul
Goodmonth 25 – Luna full (holy to Olidammara)
Goodmonth 26-28 – Miner’s Fairs
Harvester 1 – Holy to Ralishaz
Harvester 8-14 – Logger’s Fest
Harvester 11 – Luna new (holy to Nerull)
Harvester 14 – Holy to Phaulkon
Harvester 20 – Raksha Bandhan (holy to Berei)
Harvester 20 – Autumnal Equinox (holy to the Old Faith)
Harvester 25 – Luna full (holy to Olidammara)
Harvester 27 – Holy to Hieroneous
Harvester 28 – Holy to Trithereon
Brewfest 1 – Osson’s Ride
Brewfest 4 – Almor’s Tears (holy to Wenta)
Brewfest 7 – Liberation Day (holy to Dalt)
Patchwall 2 – Holy to Pelor
Patchwall 4 – Luna new (holy to Nerull)
Patchwall 7 – Bellringer’s Feast
Patchwall 14 – Lammas
Patchwall 18 – Luna full (holy to Olidammara)
Patchwall 18 – Wiccrhys (holy to Obad-hai)
Patchwall 20 – Holy to Bralm
Patchwall 25 – Holy to Iuz
Ready-reat 1 – Holy to Zagyg
Ready-reat 4 – Luna new (holy to Nerull)
Ready-reat 5 – Turning of the She-bear Stone
Ready-reat 7 – Festival of Hope (holy to Zodal)
Ready-reat 11 – Day of Remembrance
Ready-reat 12 – Day of Reflection
Ready-reat 13 – Day of Retribution
Ready-reat 14 – Great Freeday
Ready-reat 18 – Luna full (holy to Olidammara)
Ready-reat 25 – Holy to Delleb
Sunsebb 2 – Holy to Pelor
Sunsebb 4 – Luna new (holy to Nerull)
Sunsebb 4 – Holy to Beory and Cyndor
Sunsebb 7 – Holy to Xan Yae
Sunsebb 10-11 – Luna Pax (holy to Boccob)
Sunsebb 13 – Holy to Raxivort
Sunsebb 14 – Holy to Phaulkon
Sunsebb 18 – Luna full (holy to Olidammara)
Sunsebb 21 – Feast of Telchur (holy to Telchur)
Sunsebb 21 – Winter Solstice (holy to Wee Jas and the Old Faith)
Sunsebb 23 – Marihwyd
Sunsebb 25-28 – Days of Thought (holy to Rao)
Sunsebb 28 – Last day of the year (holy to Tharizdun)