By Cassandra Morgan
If you thought this past January was hotter than previous years, the statistics prove you right, with the month smashing decades-old weather records.
Melburnians have endured a run of unbearably sticky nights, notching up a mean minimum temperature – the coldest it gets at night – of 18.3 degrees over January, the warmest average minimum for any month since records began in 1855. Last month’s figure beat the previous record by about 4 degrees.
Finding somewhere to cool down has been important, as Ines Venencie and Daniel Suarez found out at the tennis.Credit: Eddie Jim
According to the Bureau of Meteorology, the city also equalled a 1974 record for the most days in a month above 30 degrees, with 17. Melbourne also recorded a run of seven days above 30 degrees for the first time since March 2013.
The hottest day of the month for Melbourne, measured at Olympic Park, was January 1 when the mercury peaked at 37.1 degrees and notched up a minimum of 20.5 degrees. The hottest minimum temperature was on January 28 when 21.7 degrees was recorded.
The lowest maximum temperature was recorded on January 8 at 19.7 degrees, while the lowest minimum temperature was recorded on January 20, when it got down to 12.9 degrees.
Bureau duty forecaster Jonathan How said the temperatures were above average right across Victoria for both minimums and maximums, owing to a lot of cloud cover and humid air flowing across the state.
University of Melbourne climate science lecturer Andrew King said climate change was increasing the frequency and intensity of heat extremes.
“We’ve seen ... an unusually high number of very warm days into the 30s [in Melbourne],” Dr King said.
“Obviously, this past month we saw a new joint daily record for Australia, with the 50.7 degrees in northern [Western Australia].
“As the climate continues to warm, we’re going to see more heat records, we will see more days over 35 [degrees] and more days over 40 as well – that will happen – and also the possibility of days over 45 or even 50 in Melbourne.”
“If we keep emitting greenhouse gases and keep warming the planet, it’s possible that in a few decades’ time ... mid-21st century there’s a reasonable chance we’d be having 50-degree days in Melbourne and Sydney.”
Humidity in Melbourne was also at record levels through January, with “dew point” temperatures – which show how much moisture is in the air – exceeding previous monthly records by substantial margins.
“We measure [humidity] by looking at the dew point temperatures at 9am and 3pm, and they’re well above average due to La Nina, with a lot of moisture coming down from the north,” the bureau’s Mr How said.
It was Victoria’s eighth-wettest January on record, and its wettest since 2011 – the last time the La Nina weather event occurred– with statewide rainfall 90 per cent above-average.
The state’s north-east notched up some of the highest rainfalls on record in January. Rutherglen and Wodonga both recorded their wettest ever month, with 274 millimetres and 269 millimetres of rainfall respectively, which the bureau said was approximately six to seven times the monthly average of 45 millimetres.
Albury also recorded its most rainfall in a single month with 306 millimetres.
Melbourne recorded 79.6 millimetres of rainfall in January, about 33 millimetres above the average.
Mr How said in the state’s far west, “it’s been the opposite story, with very dry conditions right across the South Australian border”.
“They’ve received very much below-average rainfall,” he said.
“[This summer’s La Nina] helps to explain why it has been wetter than usual, particularly across the east.
“[The weather has been] warm, humid, wet and kind of in line with what we were expecting this summer with La Nina.”
Australia is in the middle of a La Nina weather event, which usually means cooler temperatures (although not necessarily cold), more rainy days and higher risk of stormy weather. El Nino, at the other end of the spectrum, brings hotter temperatures and less rainfall. Both originate in the Pacific Ocean.
Dr King said while climate change was probably having an effect on weather systems like La Nina and El Nino, it was “subtle” compared with the impacts on heatwaves and heat extremes.
The bureau issued a severe thunderstorm warning for parts of north-east Victoria on Tuesday, with a humid and unstable air mass likely to produce “intense” rainfall and damaging winds.
VicEmergency also sent out a “watch and act” alert, urging people in areas including Bright, Mount Hotham and Falls Creek to prepare to take shelter and avoid potentially life-threatening flash flooding.
With Tom Cowie
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