TONGA has declared a pre-emptive state of emergency as severe tropical cyclone Ula batters the tiny Pacific kingdom and tracks towards Fiji, where many Australians are believed to be holidaying.

It’s the first tropical cyclone of 2016 in the Pacific, with the category three system passing close to several islands in Tonga, bringing 150km/h winds and the potential of “major property damage”.

Tongan Prime Minister Akilisi Pohiva took the precautionary action because “an emergency is happening or is about to happen”, with destructive winds and rising sea levels.

“It is necessary for the emergency powers to be exercised in order to prevent or minimise the loss of human life, illness or injury, property loss or damage and damage to the environment,” he said.

Cyclone #Ula, the last TS of 2015 is now the first of 2016 nearing Tonga in the South Pacific as a Category 2 storm. pic.twitter.com/62Hsz6wbCJ — UW-Madison CIMSS (@UWCIMSS) January 1, 2016

Laitia Fifita from Tonga’s Met Service on Tongatapu said flash flooding is expected in Vava’u.

“It is expected that the speed of movement of the tropical cyclone will speed up a little bit, so at around midday today it is expected to lie further west out of from the island of Vava’u and continue on a south southwest direction,” he told Radio New Zealand International.

Late Saturday morning, the Category three storm was passing near the northern island of Vava’u where there were reports of damage to crops and houses.

Ula has the potential “to cause major property damage, significant infrastructure and crop damage, local power failure and there is a high risk of injuries from a category three cyclone,” the official Tropical Cyclone Warning Centre said in an advisory.

It warned of “very destructive winds” and a damaging swell to develop overnight with “very high to phenomenal seas” causing flooding in low-lying areas.

A year ago Tonga was hit by Cyclone Ian which left one person dead, 4,000 homeless and destroyed crops on outlying islands.

Weather experts have predicted Cyclone Ula will directly hit the Lau Group in Eastern Fiji.

The system is expected to weaken on Sunday as it heads towards Fiji.

The Australian Department of Foreign Affairs and Trade said “all Australians (are encouraged) to register their travel on the Smartraveller website at http://smartraveller.gov.au”.

The Australian government’s current advice level for travellers heading to Fiji is listed as normal with a standard warning to “exercise normal safety precautions”.

Australian tourist Ashleigh Watt - who is holidaying in Denarau, Fiji - told news.com.au there was no sign of the cyclone in Fiji yet.

“We’ve heard about the cyclone but nothing about the mood of tourists or staff has changed,” Ms Watt said.

“Everyone is cool, drinking cocktails by the pool and soaking up their holidays.”