2019: Begins at 00:00 December 11 nd 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)
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

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.

Between 2013 and 2015 a schism arose among Solstmas RFC committee. The 3.0 date selection 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)

As of 2013, Solstmas in the United States has been redefined to start on the evening of the day before 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 2014, the "starts the day before thanksgiving" rule has been flatly rejected by all voting members of the Solstmas RFC committee. A new proposal will be finalized prior to the end of January 2015. New proposals are invited. The loss of the lunar calendar connection was missed by 100% of Solstmas users reporting back as of Dec 18, 2014. Complaints included that any similar solution to the definition would tie it too closely to commerical interests. Other possible solutions to the current problem is to define a pre-solstmas period or a Solstmas Prologue.

2009: Began unknown ; end unknown (archival research required)
2008: Began 0:00, the morning of December 17, ending 23:59pm Jan 4.