As New Zealanders sleep off their New Year celebrations, much of the rest of the world is still counting down to 2018, with global leaders revealing their goals for the next 12 months.
The new year has been greeted with fireworks in Hong Kong, Pyongyang and Sydney in the past few hours.
About 1.6 million people watched the New Year fireworks around the edge of Sydney Harbour, where a rainbow waterfall off the Sydney Harbour Bridge celebrated the legalising of same-sex marriage.
Hundreds of thousands of people will be in New York's Times Square later today to watch the giant New Year's Eve ball drop at midnight, undeterred by bitter cold weather and an unprecedented security operation.
The temperature in midtown Manhattan is expected to plunge to about -12 degrees Celsius, making it the second coldest New Year on record.
Thousands of police will be on hand, some of them heavily armed, as part of a beefed-up security plan that follows a spate of terrorist attacks in the city.
In the UK, there have been warnings that celebrations could be scuppered by travel disruption and stormy weather.
Storm Dylan is forecast to bring high winds to Northern Ireland and parts of Scotland but Hogmanay organisers in Edinburgh say it will still go ahead.
Meanwhile, a 24-hour rail strike could cause delays for partygoers travelling in or out of London's Waterloo.
In central London, rain should hold off for the New Year's Eve firework display, expected to be watched by more than 100,000 ticket holders from the banks of the River Thames.
The soundtrack will be dominated by female artists, including Aretha Franklin, Ariana Grande and Florence Welch, to mark the centenary of women getting the vote.
At midnight, Big Ben will chime again, having been turned back on over the festive period.
World leaders mark the changing of the year
In a speech, French President Emmanuel Macron vowed to rapidly push through economic and political changes in France over the coming months and said he would seek to jolt Europe into reforming too.
The televised New Year's speech was the 40-year-old president's first year-end address following his electoral victory in May. Macron made clear he would tackle even potentially thorny domestic issues, like a new immigration law.
Mr Macron, who left political rivals reeling when he won power barely a year after launching a new centrist movement, has already rattled his way through an overhaul of French labour rules, in spite of street protests and a pushback from unions.
"I will ensure all voices, including contrary ones, are heard. But all the same, I will not stop acting," Mr Macron said, seated a marble table in his office at the Elysee Palace.
The formula of the speech was largely in keeping with the one favoured by many of his predecessors, despite speculation Mr Macron would seek to shake up France's New Year presidential rite of passage too.
German Chancellor Angela Merkel has used her New Years address to promise to address growing social divisions.
Mrs Merkel is under pressure after three months of failing to form a new conservative-led coalition.
She has promised increased investment in security and defence, improved health care and education, and efforts to overcome growing urban-rural disparities.
Her popularity has waned since her efforts to form a coalition with two smaller parties collapsed in November.
A poll released on Saturday suggests that nearly two-thirds of voters want her to resign if ongoing coalition talks with another party fail.
Pope Francis in his year-end message said that 2017 had been marred by war, lies and injustice, and he urged people to take responsibility for their actions.
At his last public event of the year, an evening vespers service in St. Peter's Basilica, the pontiff said that humanity had "wasted and wounded" the year "in many ways with works of death, with lies and injustices".
While war was the most obvious sign of "unrepentant and absurd pride", many other transgressions had caused "human, social and environmental degradation".
"We must take responsibility for everything before God, our brothers and our creation," he said.
China's leader Xi Jinping has suggested his country will play a greater role in international affairs in 2018.
In a speech to mark the New Year Mr Xi said the world now expects a clear stance from Beijing on international issues.