'Heat spike' this weekend as winter loosens its grip on city

Winter's grip will finally feel like it's loosened amid a "heat spike" this weekend - even if that season's squeeze was not a particularly tight one.

Nationally, Australia had its warmest winter by maximum temperatures since records began in 1910, with days on average 1.9 degrees warmer than normal. That beat the previous record winter in 2009 by 0.3 degrees.

One influence driving the abnormally mild condition was the band of high pressures that sat further south than normal over the continent, keeping cold fronts at bay. Climate change was also a factor.

"You have the underlying long-term warming trend," Blair Trewin, senior climatologist at the bureau, said. "Consistent with that, 19 of the last 20 winters have had above-average maximum temperatures."

Nationally, August was less extreme than June and July, with temperature anomalies less pronounced and better rains across south-eastern Australia helping to ease rainfall deficits in many areas.

Forest fire index levels, though, remain high, particularly for inland NSW, as authorities prepare for an early bushfire season.

For Sydney, the city had its driest winter since 2009. The 211.4-millimetre tally for the three months was about a third below average. July and August alone, though, were the driest in 22 years, Weatherzone said.

Sydney had its seventh-warmest winter for daytime temperatures, in line with last year.

The season also included the city's warmest July day on record, with 26.5 degrees on July 30 beating a record that had stood since 1990, the bureau said.

(See bureau chart below of average maximum temperatures.)

Brief burst of spring

Similarly warm conditions should return for the first weekend of spring, encouraging many to venture outdoors amid a "temporary heat spike", Graeme Brittain, a meteorologist from Weatherzone, said.

For those heading to the beach, "sheltered, south-facing beaches will be the place to go", particularly on Sunday when northwesterly winds pick up.

On current forecasts, Sydney is tipped to reach 22 degrees on Saturday and 28 degrees for a clear if windy Sunday.

Warmer conditions are on the way, at least for this weekend.

Warmer conditions are on the way, at least for this weekend. Photo: Nick Moir

Spring's volatile weather will be on display, with large and powerful surf predicted for Saturday. Winds will also gradually strengthen on Sunday, reaching 50km/h as a cold front moves through, Mr Brittain said.

"It's a very cold air mass," he said, adding that it will knock daytime temperatures below the September average of 20 degrees for much of next week before conditions warm again by next weekend.

The cold front is also a dry one, as is the next one, meaning there is unlikely to be much rain relief soon for Sydney's threadbare playing fields.

"There's no really significant rain forecast for the next 14 days," Mr Brittain said.

Dry times

Those dry conditions also extend across much of the country after the driest winter since 2002.

Rainfall was about 43 per cent below the norm, the bureau said. (See chart below.)

NSW was notably dry, with about half the typical rain, or 58.8 millimetres. It was also the state's driest winter in 15 years.

Good rains in June meant only a small pocket of the state's north-east enjoyed above-average rain for the season.

For Sydney, rain fell on 22 days during winter, down from the average of 34 days. Just five of them had more than 10 millimetres, compared with eight such days in a typical winter.

With fewer rain clouds around, the city enjoyed sunnier-than-usual conditions, particularly in July and August.

Cool nights

One consequence of limited cloud cover, though, were cool nights, particularly for inland areas.

Sydney's nights remained milder above average for the city, but dropped below the winter average in western suburbs. Minimum temperatures in Parramatta, for instance, were 0.6 degrees below normal, the bureau said.

Likewise for NSW, central and southern parts of the state recorded below-average nights, often accompanied with frost.

Dr Trewin said Bathurst stood out as one location enduring extreme conditions during winter.

The town posted its highest average maximums for the season, its coldest average nights since 1927 and its driest winter on record.

Nationally, average minimum temperatures were 0.34 degrees above the long-term norm, although the cold was particularly centred over the country's south-east. (See bureau chart below.)

After a slow start, the ski season got a boost from some big dumps of snow. Spencer's Creek had 189 centimetres of snow at the end of August, the most since 2012.

More snow is expected in the coming weeks, Dr Trewin said.

The bureau's forecasts for spring, updated on Thursday, point to a switch in coming months towards more typical rainfall levels.

That news will be welcomed by farmers but also fire authorities, particularly in NSW, that are gearing up for an early and active bushfire season.

"The seasonal outlook for spring rainfall does lean to wetter-than-average conditions in a lot of the south-eastern corner of Australia, particularly along the east coast," Dr Trewin said.

"It does look like we're going to see a bit of a pattern shift," he said, although the change for some regions may not arrive until October.

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

This story 'Heat spike' this weekend as winter loosens its grip on city first appeared on The Sydney Morning Herald.