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East coast low and record heat: It's 2016, a year of weather extremes for Sydney

Peter Hannam
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Garry Silk's idyllic lifestyle on Sydney's northern beaches took a hammering during the ferocious storm that battered and drenched much of Australia's east coast in June.

Almost three years to the day after moving into his Collaroy residence, Silk, his family and neighbours were forced to evacuate as cyclonic-strength winds combined with a king tide to snatch as much as 50 metres of beach, exposing foundations of homes that needed mass sandbagging to save them.

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"We used to walk down over the dunes to the beach, it was lovely," the property developer says.

Now, with summer in full swing, Silk and his neighbours are coming to terms with the loss of privacy along with fences, gardens and in the case of the McGuinness family a few doors along, a swimming pool that was up-ended, and became a symbolic image of the storm's might published around the world.

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That pool now sits covered by sand, forming part of the sea wall until more permanent solutions can be found.

Just recently, he says, one neighbour had two beachgoers plonk themselves on his outdoor bench, overlooking what remains of the garden amid the detritus of fragmented picket fences and rubble.

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"He asked them: 'What are you doing'? and they just replied: 'We're taking in the view'," Silk says.

Most significant event

The storm was generated by a monster east coast low, arguably the state's most significant weather event in 2016, if not Australia's.

In its special climate statement on the event, the Bureau of Meteorology list the tempest's remarkable features. For NSW, it dumped an average of 73.11 millimetres of rain along the state's coastline, the most ever for a single day for any month, beating the previous high set on January 19, 1950, of 68.89mm.

The scale of this mid-latitude cyclone also stretched further, from Queensland to Tasmania, where it broke the Apple Island's drought with record rains.

Also, to underscore the tropical features of the event, all previous storms approaching the amount of rain dumped on eastern NSW had occurred during summer rather than the start of winter, and were linked to tropical cyclones or former ones.

As with other big natural events, social, economic and environmental impacts have lingered long after the storm. Insured losses alone were about $250 million. It has also laid bare vulnerabilities, particularly for coastal communities, of the more intense storms expected as the climate warms. The challenges facing governments include trying to boost resilience and adaptability for residents in a manner that's fair and foresighted.

While major east coast lows have hammered the coastline previously, such as in 1974 and 1978, impacts are likely to worsen with climate change, researchers including Acacia Pepler, a bureau climatologist and UNSW scientist, have found.

For one thing, a warmer atmosphere can hold more moisture – 7 per cent more per degree of warming – and therefore dump more rain. The impact of storms on coasts will also likely be made worse by rising sea levels, with storm surges riding on a higher base.

And, some on the government have noted, the direction of the storms might change, exposing communities and properties usually shielded by destructive weather.

"No one ever thought the storm would come from the north," says Warren Hughes, a resident of Wamberal on the NSW Central Coast. "I was petrified."

Hughes' home was one of dozens which had their dune buffer scoured out by the June storm. (See photo below, taken this week by James Brickwood of one Wamberal residence.)

Record-breaking heat

For Sydney, 2016 had other noteworthy weather, perhaps none more so than the outstanding warmth even if heatwave peaks weren't as frequent as the summer of 2013-14.

As parts of Sydney closed out 2016 with their first 40-degree readings of the summer, the year's last burst of heat was a fitting end to the city's hottest year on record, Weatherzone says.

Sydney will notch its highest readings since reliable data gathering began in 1858 for each of the main measures: for minimum, mean and maximum temperatures.

For day-time temperatures, the city's average day in 2016 will come in at about 23.8 degrees, and nights about 15.5 degrees, Weatherzone estimates. The bureau will release its assessments next week.

For perspective, it's as if Sydney's average year-round conditions matched those of a typical November.

Compared with long-run average, days were about 2 degrees warmer than normal and nights 1.5 degrees. Should similar anomalies by overlaid on 2016 in future years – an increase within the bounds of projected climate change – year-round temperatures would start to feel like a typical December.

'Persistent warmth'

Looking back over the year, Sydneysiders might be forgiven for thinking 2016 was not a remarkably hot year – the last few days notwithstanding.

The city did set a few high marks, including the hottest April day on record with 34.2 degrees set on the 6th. December 14 was another standout with its warm minimum of 27.1 degrees, the hottest overnight temperature for the month but the second for any month.

But generally few months set new high marks and autumn was the only season to do so for mean, minimum and maximum temperatures. The average of day and night temperatures easily eclipsed the previous high set in 2014 by 0.4 degrees, the bureau says.

"It's mainly due to those cold days not being so cold," says Joel Pippard, a Weatherzone meteorologist. "The southerly changes have been fairly weak."

Blair Trewin, senior climatologist at the bureau, highlights Sydney's extended runs of relatively warm weather, such as the "persistent hot spell" that ran from February 19 to March 14. Those 25 days all exceeded 27 degrees, more than double the previous record run for any time of the year of 12 such days.

A slew of other Sydney high marks were set in 2016, such as the record 25 nights in a row above 20 degrees. The mercury on seven of them remained above 22 degrees, compared with a typical year, when just 0.4 of them might be expected to do so.

"We had anomalously high sea surface temperatures along the coast, so sea-breezes didn't have the cooling effect they would normally have," says Dr Trewin.

Along the way, the city quietly clocked up a record 232 nights when the temperatures remained above 12 degrees, a series that ended on May 18.

Barring some final temperature spikes in the current heatwave, Sydney and NSW clocked their hottest day for the year early in the piece. For Sydney that was 39.2 degrees reached on January 14 and 46 degrees for Hay in the Riverina a day earlier.

Nationally, the high points came in February, where two Pilbara sites, Mardi and Emu Creek, touched 47.8 degrees on the 12th and 13th, respectively, says Dr Trewin.

Other big wets

Cricket fans, though, probably remember January for being wet in Sydney, with the New Year's Day Test match being washed out with only an innings and a half produced by the West Indies and Australia combined.

In fact, it was the city's wettest January since 1988 and included the coolest day – with just 18.6 degrees recorded on the 6th at Observatory Hill – since 1978, the bureau says.

Rainfall for the month was almost 250mm and more than double the average, although the eight days above 30 degrees – the most since 1991 – also gave the city a tropic feel.

Rain was another big feature of NSW's and indeed Australia's year. The village of Coramba on NSW's mid-north coast may grab the record for most rain in a single day in 2016, with 430mm collected in the gauge on June 15, says Dr Trewin.

September was the state's wettest on record for that month, with triple the usual rain. Following the third-wettest winter, it meant large parts of inland NSW were under water for weeks, such as around Forbes.

A flooded Newell Highway between Forbes and West Wyalong in September.

A flooded Newell Highway between Forbes and West Wyalong in September. Photo: Wolter Peeters

"All of those inland flowing rivers had pretty significant floods," says Dr Trewin, adding that inflows into the Murray are only recently peaking, so slow is the movement of water across the largely flat inland regions.

Nationally, "the big story this year is the sudden transformation of very dry conditions in April to very wet period", he says. The seven months to April and the seven subsequent months perhaps best show that transformation.

For the period up to April, large areas of eastern Australia were in drought. (See bureau chart for the seven months from October 2015.)

Over the next seven months, large parts of inland Australia had recorded their best rains in years. (See bureau chat below for the May-November period.)

With so much water to evaporate, national temperatures were also moderated, although the country is still expected to come in at about the fifth warmest on record.

For coming months, odds favour a relatively hot start to 2017 for Sydney and for most of NSW. Conditions were also expected to be on the dry side, a combination that could keep fire authorities busy.

Weatherzone is owned by Fairfax Media, publisher of this website.

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