The restart of Sydney's desalination plant is proceeding faster than expected, helping to slow the drawdown of the city's reservoirs amid the ongoing drought.

The past five years have been the hottest on record.

Sydney sweated through its hottest December night in 15 years overnight, but a cool change - and a good drenching - is on its way.

Queanbeyan and Molonglo rivers have been issued a severe weather warning and remain on flood watch.

The trail of destruction left behind suggests the supercell storm that struck Forbes Creek south of Bungendore on Saturday was a tornado, on the same night Canberra had its highest daily rainfall for the month.

Canberrans spent much of Valentine's Day looking for ways to cool off and beat the heat as the capital sizzled.

Canberra's temperatures varied by more than 35 degrees during a warmer, drier summer than average, meteorologists say.

Sydney is in the midst of a spider boom, with "perfect conditions" leading to more offspring than usual surviving and resulting in many plants and other objects being draped with silken webs, according to the Australian Museum.

For the first time this year the mercury has dipped below zero in Canberra.

A strong cold front will sweep over much of Australia over the weekend, bringing potentially the largest outbreak of frigid conditions in 15 years, the Bureau of Meteorology said.

The powerful El Nino continues to intensify in the Pacific and is now the strongest since the record-breaking 1997-98 event, the Bureau of Meteorology said.

Sydney's run of exceptionally chilly mornings will take a break for a few days but a return to sustained milder conditions may be weeks away.

Air pollution was higher in Sydney's north-western suburb of Prospect on Friday morning than it was in Beijing at the same time. 

Sydney is in for gusty winds on Wednesday, followed by chilly temperatures next week as Winter makes itself known.

When Steve Douglas drove by a neighbourhood street corner, he spotted a new and rare species of eucalyptus tree. After 25 years, more than a hundred of these trees are being planted in a secret location in a national park.

Googong dam has begun to spill again, as Wednesday's wet weather pushed it to capacity, while sporting grounds across the territory were shut and chaos reigned on Canberra's roads.

The Earth is in the midst of an usually long spell between ice ages and the build-up of carbon dioxide emissions through the burning of fossil fuels may postpone the next glaciation event by at much as 100,000 years, according to new climate research.

The Coodardie cattle station may not be the most likely place to find a farm in sync with nature.

It was the perfect winter weekend to stay indoors with the Perth metropolitan area drenched in rain and battered by strong winds and hail stones.

Meteorologists predicted the southerly buster would hit the city from about 5am on Wednesday, and that's precisely when it swept over Sydney Airport.

Weather-related disasters in the past two decades have killed more than 600,000 people and inflicted economic losses estimated at trillions of dollars, the United Nations said Monday, warning that the frequency and impact of such events was set to rise.

Sydney is in for another scorcher on Thursday with the potential for 40 degrees over much of the city ahead of a gusty cool change from the south.

Sydney could get its best weather for the year, with a week of gently warming days, lots of sunshine and little rain.

A major climate summit of more than 190 nations was set to run overtime as delegates struggled to narrow gaps on guidelines to reduce greenhouse gas emissions and raise aid for developing nations.

Rivers and water catchments across the state’s east coast have not had enough time to dry out since the recent flood emergency, says the weather bureau’s senior meteorologist.