In Europe, Greeks, Irish and Spaniards began partying through the night to help put a year of economic woe behind them. And in New York, nearly a million New Year's Eve revelers were expected to cram into Times Square to watch the midnight ball drop, just days after the city got clobbered by a blizzard.
As rainclouds cleared, around 50,000 people, many sporting large, brightly colored wigs this year, gathered in Madrid's central Puerta del Sol square to take part in "Las Uvas," or "The Grapes," a tradition in which people eat a grape for each of the 12 chimes of midnight.
Chewing and swallowing the grapes to each tolling of the bell is supposed to bring good luck, while cheating is frowned on and revelers believe it brings misfortune.
Police had painstakingly screened all those arriving to make sure drinks and bottles were left behind to avoid injury in the crowded square, so many quickly downed their sparkling cava wine before joining the animated party.
"It's an annual tradition and I'm here to make my wishes for the new year, if you eat the grapes your wishes will come true," said beautician Anita Vargas, 22.
As the 12th grape was swallowed, the skies above most Spanish cities lit up with fireworks that slowly filled the air with smoke and the smell of gunpowder.
2010 was a grim year for the European Union, with Greece and Ireland needing bailouts and countries such as Spain and Portugal finding themselves in financial trouble as well.
"Before, we used to go out, celebrate in a restaurant, but the last two years we have had to stay at home," said Madrid florist Ernestina Blasco, 48. She said her husband, a construction worker, is out of work.
In Greece, thousands spent the last day of 2010 standing in line at tax offices to pay their road tax or sign up for tax amnesty. "We can see that the quality of life is being degraded every day. What can I say? I don't see the light at the end of the tunnel," said Giorgos Karantzos of Athens.
New Zealanders and South Pacific island nations were among the first to celebrate at midnight. In New Zealand's Auckland, explosions of red, gold and white burst over the Sky Tower, while tens of thousands danced and sang in the streets below. In Christchurch, partyers shrugged off a minor 3.3 earthquake that struck just before 10 p.m.
Multicolored starbusts and gigantic sparklers lit the midnight sky over Sydney Harbor in a pyrotechnics show witnessed by 1.5 million spectators. "This has got to be the best place to be in the world tonight," said Marc Wilson, 41.
Hundreds of thousands of people gathered along Hong Kong's Victoria Harbor to watch fireworks explode from the roofs of 10 of the city's most famous buildings.
In Vietnam's capital, Hanoi, an estimated 55,000 people packed a square in front of the city's elegant French colonial-style opera house for their first New Year's countdown blowout, complete with dizzying strobe lights and thumping techno music spun by international DJs.
Vietnamese typically save their biggest celebrations for Tet, the lunar new year that begins on Feb. 3. But in recent years, Western influence has started seeping into Vietnamese culture among teens, who have no memory of war or poverty and are eager to find a new reason to party in the communist country.
At Japan's Zojoji temple in Tokyo, monks chanted and revelers marked the arrival of the new year by releasing silver balloons with notes inside. The temple's giant 15-ton bell rang in the background.
In Dubai, the world's tallest building was awash in fireworks from the base to its needle-like spire nearly a half-mile (828-meters) above. Sparkling silver rays shot out from the Burj Khalifa in a 10-minute display.
In France, police were on alert for terror attacks and for celebrations getting out of hand. Rampaging youths typically set fire to scores of vehicles on New Year's Eve. Interior Minister Brice Hortefeux said 53,820 police were mobilized — 6,000 more than usual.
France has been extra vigilant following threats from al-Qaida and the kidnapping of five French citizens in Niger.
Italians planned to ring in the new year with illegal fireworks, shot off in squares and alleys — a tradition that usually results in numerous hand and eye injuries. Naples Police Chief Santi Giuffre appealed to citizens to "give up or at least cut back on this" practice.
In London, higher temperatures after weeks of frigid weather were expected to draw about 250,000 onto the streets. Many planned to line the River Thames to watch fireworks and hear Big Ben toll at the stroke of midnight.
In Scotland, the four-day Hogmanay festival began Thursday night with a torch-lit procession through the streets of Edinburgh. Around 25,000 people took part, marching to the top of a hill to watch the burning of a model Viking ship. Hogmanay is derived from the winter solstice festival celebrated by the Vikings.
The Dutch celebrate by eating deep-fried dough balls covered in powdered sugar and washed down with champagne. The Danes jump off chairs to "leap into the new year." And the Austrians twirl in the new year with a waltz, carrying radios so they can dance to Strauss' "Blue Danube" as the clock strikes midnight.