Fireworks explode over Sydney Harbour during New Year's Eve celebrations in Sydney, Monday, Jan. 1, 2018. (David Moir/AAP Image via AP)
North Koreans watch as fireworks explode as part of New Year celebrations, above the Taedong River as viewed from Kim Il Sung Square, in Pyongyang, No
In this Dec. 31, 2017, file photo, a bride and groom react to their marriage documents during a mass wedding held in celebration of the New Year in Ja
People walk in popular Istiklal Street near the city's main Taksim Square as people remember the victims of a deadly New Year's attack a year ago, in
Buddhists light candles during New Year celebrations at Jogyesa Buddhist temple in Seoul, South Korea, Monday, Jan. 1, 2018. (AP Photo/Ahn Young-joon)
Filipino revelers watch as fireworks light up the sky to welcome the New Year Sunday, Dec. 31, 2017 at the seaside Mall of Asia in suburban Pasay city
Fireworks explode over the Victoria Harbor during New Year's Eve to celebrate the start of year 2018 in Hong Kong, Monday, Jan. 1, 2018. (AP Photo/Kin
Tourists watch a fireworks display in front of Malaysia's landmark building, the Petronas Twin Towers, during the New Year's celebration in Kuala Lump
Participants push away drums after a count down to the New Year event in Beijing, China, Monday, Jan. 1, 2018. (AP Photo/Ng Han Guan)
Fireworks explode with slogan reading "Happiness and Good Condition Together" on the Taipei 101 building during the New Year's celebrations in Taipei,
The torchlight procession which marks the opening of city's New Year celebrations, makes its way through Edinburgh, Saturday Dec. 30, 2017. Torchbeare
People dressed as Vikings get ready to lead a torchlight procession in Edinburgh, which marks the opening of Edinburgh's New Year celebrations, Saturd
Spectators pass through security screening ahead of the New Year's Eve celebration in Times Square in New York, on Sunday, Dec. 31, 2017. New Yorkers,
People around the world are welcoming 2018 with fireworks displays and loud cheering.
Revelers in Australia watched fireworks over Sydney Harbour. In North Korea, fireworks exploded over the Taedong River.
Elsewhere, the tone was more somber. In Turkey, some 100 people gathered outside Istanbul's Reina nightclub to remember the victims of a deadly New Year's attack a year ago. The group, holding carnations, observed a moment of silence. The attack happened early last Jan. 1, when an assailant shot his way into the nightclub, killing 39 people — most of them foreigners — and wounding 79.
In Scotland, a major windstorm caused some problems, but organizers expected Edinburgh's famed Hogmany New Year's Eve celebration to be unaffected.
In New York, revelers passed through security hours before the annual ball drop in Times Square.