These holiday dates are drawn from various Slavic traditions. Some are reconstructed holidays from reconstructionist pagan traditions. Some are continuously celebrated in their countries of origin. Many of the holidays that have been continuously celebrated down to the modern day are also celebrated by Christians. 

 October

 1 свято Матері Слави (Ukrainian Ridnoveri)

 23 свято Мокоші (Ukrainian Ridnoveri)

 25 Pokrov (Modern Rodnovery)

26 Day of the Ancients (American Russian)

27 Дідова Субота, Осінні Діди (Ukrainian Ridnoveri)

28 Paraskeva Piatnica (Belorus)

31 Dziady (Polish Rodzimowierstwo)

November

1 Днём Мокошов (Slavic Reconstructionist), Dan Mrtvih (Slovenia)

2 Dziady Jesienne (Rybakovian), Dusicky (Czech)

11 Day of Remembrance for Volvh and Goði (American Russian)

24 Свято Богині Долі (Ukraine)

30 Калита (Ukrainian Ridnoveri)

December

6 Свято Велеса (Ukrainian Ridnoveri), Mikola (Belorus), Djed Mraz (Croatia), Miklavž (Slovenia)

13 Luciaden (Dalmatia)

15 Meckin Dan (Modern Rodnovery)

21 Коляда begins (Slavic Reconstructionist, and others), Szczodre Gody (Polish Rodzimowierstwo)

22 Чортовим тижнем begins (Ukraine)

23 Свято Рода (Ukrainian Ridnoveri)

24 Zvizdary begins (Lemko, Carpathia)

25 Kolyady begins (Belorus)

28 Чортовим тижнем ends (Ukraine)

31 Коляда ends (Slavic Reconstructionist, and others)

Special thanks to Scott Simpson for providing documents on which I based some of my research for the Slavic Calendar. 

Image:  Złota bajka jesienna (Golden Autumn Fairy Tale) by Stefania Krzysztofowicz-Kozakowska via Wikimedia Commons