Australia has welcomed a new decade amid one of its worst-ever bushfire seasons.

Most capital cities went ahead with planned celebrations on Tuesday, despite calls to cancel fireworks displays and festivities in solidarity with those affected by fires.

An estimated one million people lined Sydney's foreshore to watch the $6.5 million fireworks extravaganza.

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During the event, almost $1 million was raised for communities struggling with fires and drought.

"We're proud to harness the power of Sydney's New Year to support people affected by the bushfires," the City of Sydney said.

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But just kilometres away, Liverpool, Parramatta and Campbelltown councils all cancelled their fireworks due to fire risk.

Hundreds of thousands of revellers gathered in Melbourne to watch 14 tonnes of fireworks shoot from 22 city rooftops.

Lord Mayor Sally Capp said the city's annual fireworks show was safe to hold because of the cool change that came late on Monday.

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And tens of thousands of people lined the Brisbane River to watch their New Year's Eve fireworks display.

Brisbane Deputy Mayor Krista Adams said New Year's Eve provided a boost to the city's economy.

"People book these events a year out to stay in the hotels at South Bank," she said.

Fireworks went ahead in all other capital cities but Canberra's planned celebrations were cancelled amid a total fire ban.

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The start to 2020 came after a day where fires ravaged parts of Victoria and NSW, which left two more dead and five people missing.

In the lead up to midnight, many on social media noted the mood around the country was far more sombre than in previous years.

I wish everyone in Australia a safe New Year. I wish I could say happy, but there is nothing to be happy about at all when our beautiful country is being decimated by these climate change driven bushfires. Real CC action is required. The clock is ticking, but not for midnight. pic.twitter.com/QtnsvFRji4 — 💧🌱Michael Springer (@MichaelSpring17) December 31, 2019

Wishing everyone a Happy New year. My thoughts are with everyone in Australia affected by the bushfires tonight 🙏. A mate of mine took this photo yesterday😢 📸 Matty Hol. pic.twitter.com/ANkWn96Qv4 — Jason Ohalloran 2⃣2⃣ (@ohalloran22) December 31, 2019

What a horrible day in Australian history. While a lot of us are lucky to see in the new year without incident. Spare a thought for all those fighting and suffering from the bushfires. 🙏🏻 #AustralianFires — Stephen Quartermain (@Quartermain10) December 31, 2019

Happy New Year from Australia's east coast. A bit sombre here with the bad bushfires going on. But may 2020 have much joy. — David Jinglebells (@djackmanson) December 31, 2019

Prime Minister Scott Morrison used his new year's message to urge Australians to be grateful they live in the "most amazing country on earth".

"The wonderful Aussie spirit that means we always overcome whatever challenges that we face that we always look optimistically into our future," he said.

"There's no better place to raise kids anywhere on the planet."

But the message drew criticism on social media.

“there’s no better place to raise kids anywhere on the planet” ~ #SmoKo pic.twitter.com/eJA7iBRZ28 — 🐲 The Bunyip 🎄 (@WrittenOnWater) December 31, 2019

What is the matter with him? Our country is burning. People are in the front line. He is not understanding the situation at all. Politicians are not going to help us. Experts will. People who love and care will. Those will skills and knowledge. We shall help each other. — 💧Cathy Woods (@sally07) December 31, 2019

During a performance on ABC TV's live broadcast, musician Tex Perkins made an obscene gesture in the direction of the prime minister's Sydney residence, Kirribilli House, saying: "This one's for the prime minister, it's called the honeymoon is over".

Tex Perkins: “This one’s for the Prime Minister, it’s called The Honeymoon is Over” (directs bird toward Kirribilli).



The right will be going off their nut when they hear about this aired on the ABC. #Smoco #SenateInquiryPending #SydneyNYE #DonateToTheRedCross pic.twitter.com/kiHVhHKyh9 — Sotiris Cominos (@SoggyTiri) December 31, 2019

While Victorian Premier Daniel Andrews summed it up as "a tough start to 2020".

Usually I'd just be wishing you all a happy New Year – but it's a tough start to 2020 for lots of Victorians.



So to everyone affected by the bushfires, and to our fireys, emergency workers and volunteers putting their lives on the line: stay safe.



And thank you. — Dan Andrews (@DanielAndrewsMP) December 31, 2019

Additional reporting: AAP