December 26, 2021 (Sunday)

Iran's Islamic Revolutionary Guard Corps releases a video on social media threatening to destroy the Israeli city of Dimona and a nearby nuclear facility in the Negev desert.

A massive Roman castrum dated to the reign of Caligula is discovered in Velsen, Netherlands. The site is the most northern fort found by archaeologists, and believed to be a stationing port of Caligula’s failed invasion of Britain.

New South Wales reports a record for the second consecutive day of 6,394 new cases of COVID-19.

China reports 206 new cases of COVID-19 in the past 24 hours, which is the highest single-day total of new cases in 21 months, thereby bringing the nationwide total of confirmed cases to 101,077.

Iran bans all travellers from the United Kingdom, France, Denmark and Norway for 15 days and indefinitely suspends all land travel to Turkey due to the spread of the SARS-CoV-2 Omicron variant.

The Gaza Strip reports its first locally transmitted case of the SARS-CoV-2 Omicron variant.

Kosovo reports its first cases of the SARS-CoV-2 Omicron variant in two people who travelled from the United States, a person who travelled from France, two people who travelled from the United Kingdom, and four people with no international travel history.

Algeria begins to implement vaccine passports as a precondition for people to enter or leave the country and also for people to enter a wide range of public venues such as sports facilities, theatres and museums as part of an attempt to increase the country's low COVID-19 vaccination rate.

Oman's Supreme Committee announces that all incoming expatriates over the age of 18 years who want to enter the country must show proof of at least two doses of the COVID-19 vaccine as well as a negative PCR test from the previous 72 hours. They also announce that the ban on travelers from South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, and Mozambique will be lifted.

Northern Ireland imposes tightened COVID-19-related restrictions, which include closing nightclubs and banning indoor seating at events, restricting socialization to three households, and reintroducing the rule of six at bars, restaurants, and pubs that only offer table service.

South Australia reports a record 744 new cases of COVID-19 in the past 24 hours, thereby bringing the statewide total of confirmed cases to 4,324.

Kodiak, Alaska sets the highest temperature ever recorded in December in the state of Alaska, reaching 19.4 °C (66.9 °F). The Aleutian Islands and island communities in West Alaska have seen abnormally high temperatures since mid-December, including eight straight days of over 10 °C (50 °F) in Unalaska, including 13.3 °C (55.9 °F) on Christmas Day, the warmest Christmas temperature on record for the state. Temperature anomalies for late December reach 10–15 °C (18–27 °F) in some areas. The state also lately experiences unusually wet spells of weather.

The Taliban regime dissolves Afghanistan's Independent Election Commission, saying that "there is no need for these commissions to exist and operate".