2020: Begins at sundown on December 10, 2020 and ends 23:59 on Jan 6 [or 23:49 Jan 5] (via Solstmas Calc:2.3)
2019: Begins at 00:00 December 11 and ends 23:59 on Jan 6 [or 23:49 Jan 5] (via Solstmas Calc:2.3)
2018: Begins at sundown December 2 and ends 23:59 on Jan 4 [ or Jan 6 (Solstmas:Calc2.4)] (via Solstmas Calc:2.3)
2017: Begins at sundown December 12 and ends 23:59 on Jan 4 [calc2.4 suggests ending Jan 8] (via solstmas calc 2.3)
2016: Begins at 0:00 on December 14 (???) and Ends 23:59 on Jan 6 [calc2.4 would have it ending Jan 8] (solstmas calc 2.3)
2015: Begins at sundown, December 6 and Ends 23:59 on Jan 6 (solstmas calc v2.2)
Solstmas RFC Wiki
Solstmas is a new holiday term and meme to replace the many problematic, half-hearted, and anemic inclusive terms for the winter holiday period between mid-December and early January when non-retail business grinds to a halt in many parts of the world.
Solstmas is currently in draft mode, you can contribute! Solstmas is scheduled for live roll-out for the 2026 Solstmas, but is currently in beta testing. Solstmas is an open-source, community-defined holiday meme designed to be inclusive of every tradition and modern celebratory or slackful practice. It is both intended as a naturalistic descriptor of the period and cultural forms including Hannukah, Solstice, Christmas, Qwanza, New Years, business world nothing done-ism, humbugging, celebratory revelry and gluttonous indulgence.
During this beta-testing period, please see the Solstmas Wiki for more details and to contribute.
In 2013, Solstmas was redefined (Solstmas Calc 3.0) to start on the evening of the day before US Thanksgiving and ending on January 4th or, if Jan 4th is on a Friday, Saturday, or Sunday, the first Monday following the 4th of January. The schlepp appears permanent.
After a trial run in 2013 and 2014, the Solstmas Calc 3.0 ("starts the day before thanksgiving") rule was flatly rejected by a majority of voting members of the Solstmas RFC committee. Due to the schism, a temporary measure was enacted and Solstmas date calculations were reverted to Solstmas 2.3.
New proposals for how to integrate the "Black Friday/Cyber Monday" have not yet materialized, the committee continues to accept new proposals, one of which is a "Pre-Solstmas" period ("Solstmas Prologue" was one proposal) with different parameters and greetings. All of the Solstmas RFC Comittee are in favor of continuing to tie specfic Solstmas dates to a lunar calendar as well as a Roman-Solar calendar. Proposals should not be tied solely to commerical interests.
Solstmas Calc 2.3: Solstmas begins either at sundown on the first day of Hannuka or at midnight. startDate = min(EruvChanukah, Dec11) and endDate = max(lastDayOfChanukah, lastDayOfChristmas, ThreeKingsDay, Epiphany).
Solstmas Calc 3.0 was an algorithm that began the day before US Thanksgiving resulted in disagreement and discord. Date algorithm has been reverted to 2.01 : start = min(EruvChanukah, Dec11) and end = max(lastDayOfChanukah, lastDayOfChristmas, ThreeKingsDay, Epiphany)
2014: Begins at sundown, November 26, Ends 23:59 on Jan 5 (solstmas calc 3.0)
2013: Begins at sundown, November 27. Ends 23:59 on Jan 5 (solstmas calc 3.0)
2011: 00:00:01 Dec 17 2011, ends 23:59 Jan 4
2010: Began at sundown, on the evening of December 1, ending 23:59 Jan 4
2009: Began unknown ; end unknown (archival research required)
2008: Began 0:00, the morning of December 17, ending 23:59pm Jan 4.