Hottest July on record
Australia has had the hottest 11 months on record since September says Fairfax environmental reporter Peter Hannam.PT0M0S 620 349
It's fair to say tales of abnormally warm weather in Australia sound like broken records - because for the most part they are.
This year has already seen the hottest day, month and season on record, and after a warm July - about 1.5 degrees above the long-term norm - the hottest 11-month period on record. July itself will come in as the nation's third-warmest.
Come on in: Balmy temperatures lure surfers to Bondi Beach. Photo: James Alcock
As Melbourne's mercury reached 15 degrees on Wednesday, the city will post record July warmth in more than 150 years of counting.
Sydney has enjoyed maximum temperatures about 3 degrees above normal, topping the previous record July average of 19 degrees by about a third of a degree. Wednesday's maximum came in at 18.4 degrees.
It will require ''quite a dramatic change'' for 2013 not to be among the hottest years on record for Australia, said David Jones, head of climate analysis at the Bureau of Meteorology.
Year to date, average mean temperatures are running 1.07 degrees above the 1961-90 baseline, placing the year just behind 2005, the hottest in more than a century of national data.
The exceptional warmth began last September and every month has turned in notable weather.
Sydney, for instance, had its warmest day, at 45.8 degrees back in January, a March with every day above 20 degrees, and the most July days of 20 degrees or warmer with Tuesday marking the 12th - two more than the previous record set in 1975.
Melbourne, meanwhile, notched nine consecutive days above 30 degrees in March - eclipsing the previous string of seven set in February 1961 - and the longest stretch of days above 22 degrees in May. July 18 was the city's warmest July day, with temperatures reaching 23.3 degrees.
Both cities recorded just three days below average for the month. ''Cool days are less common but are also not as cool as they once were,'' Dr Jones said.
Snow season among worst
Those mild conditions also stretched far inland and, unfortunately for the ski resorts, into alpine regions. Mount Hotham, for instance, had a record six consecutive days above zero during July.
''We're shaping for one of the worst snow seasons on record,'' Dr Jones said. ''It's just been so warm.''
One factor influencing conditions has been unusually warm sea-surface temperatures right around the country. To the end of June, ocean temperatures are wavering about half a degree above the long-term average, meaning onshore winds are warmer in virtually any direction they blow. In a century of records, Australia hasn't recorded a below-average temperature for 20 years, Dr Jones said.
''It does put quite a bias into our system,'' Dr Jones said. “It’s going to be very difficult for the climate over the land to offset that general influence,” with the result temperatures for the rest of the year should remain above average.
The three-month outlook is also for above-average temperatures although perhaps less exceptional than recent months, he said.
The start of August should be warmer than average for both cities. Under the current outlook, four of the first six days of the month should be above Melbourne's August average of 15, and five of the first six days should see the mercury climb above the 18-degree average for Sydney, the bureau forecasts.
Dr Jones said it is probably wrong to focus on either the land or sea as the source for the above-average warmth.
''They're both warm in part because the planet is getting hotter,'' Dr Jones said. ''It's global warming being manifest locally.''