The Markets in the states of Bavaria (Bayern) and Sachsen have been shut down. But most states still have markets in place for the 2021 season. Since the markets are such a big factor in winter visits to Germany, those with plans for Bavaria and Sachsen may want to look into other states before canceling their plans.
Christmas markets in Rheinland-Pfalz (just west of FRA airport.) Vaccination document + passport + mask required as of
Dec. 4 for entry.
Alzey (closed Dec. 25 & 26 but open AFTER Christmas through Dec. 30. Beautiful town.)
Andernach
Bernkastel-Kues (ending Dec. 19)
Bitburg
Frankenthal
Ingelheim (closing Dec. 19)
Kaiserslautern (CANCELED)
Koblenz (continues AFTER CHRISTMAS through Jan. 9)
Landau (CANCELED from Dec. 5 forward)
Ludwigshafen
Mainz (Main market closing Dec. 23 but markets on 3 in-town plazas are open through Dec. 30.)
Mayen
Neustadt an der Weinstraße (CANCELED)
Neuwied
Speyer (closing Dec. 18)
Traben-Trarbach (CANCELED)
Trier (closing Dec. 22)
Worms
Zweibrücken (CANCELED)
https://www.swr.de/swraktuell/rheinland-pfalz/weihnachtsmaerkte-rlp-2021-100.html
Christmas Markets in Nordrhein-Westfalen (north of Rheinland-Pfalz) - place names you'll recognize and other too...
UPDATE: NRW has decided the Christmas markets can remain open, but with stricter statewide Corona rules, which will soon be in place; in addition to wearing the proper mask, expect to show your passport and CDC card for a 2G inspection at Christmas market entrance gates. (AFAIK right now, there are no statewide plans like we saw in Baden-Württemberg to outlaw CDC cards in favor of digital vaccination docs.) It is possible that these new restrictions may be seen as undoable by local market organizers and some markets may close. I'll try to keep this list current, but you should check current status for these places if any are in your plans.
CLOSING DATES: Most will end on Dec. 22 or 23.
Aachen
Bonn
Dortmund
Duisburg
Düsseldorf (closed Dec. 25 but open through 12/30.)
Essen
Cologne
Mönchengladbach
Münster