Key Points
- Warmer days and nights than usual are predicted around Australia this Autumn.
- Below-average rainfall is expected for northern regions, according to the Bureau of Meteorology.
- Warmer conditions are expected to persist as summer’s duration lengthens, according to an expert.
Martin Murray, an agronomist from Delungra in northeastern New South Wales, always checks the weather forecast first thing in the morning.
“The first thing I do when I get out of bed in the morning is to check the weather, and the last thing I do, before I go to bed, check the weather, and then I probably check it about another 20 times during the day,” Murray said.
Murray’s farm predominantly operates a rain-fed cropping system, which relies on rainfall for water.
Murray, who also manages cattle, said the latest autumn forecast from the Bureau of Meteorology was concerning.
“They said [there will be] warmer than average weather; plants are responsive to heat, and so the warmer it is, the faster they grow,”
“If they get established too quickly, too early, that’ll put them at greater risk later in the year. So we could be seeing some people delay their sowing by a little bit just because of that.”
Warmer autumn predicted for Australia
The BoM has predicted warmer-than-usual days and nights for all of Australia this autumn in the latest long-range update.
Dr Andrew King, a climate scientist at the University of Melbourne, said that it is not surprising that there will be warmer conditions on average across the vast majority of Australia.
“It’s in part because the average that’s used for these forecasts is a recent historical average,” he said.
“Because we’re warming the planet through our greenhouse gas emissions and because Australia is warming, we expect to see more forecasts for warmer than average conditions than we do for cooler than average conditions.”
King noted that predicting seasonal outlooks at this time of year can be more challenging than in the spring.
Janette Lindesay, a climatologist and Professor at the ANU Fenner School of Environment and Society, explained temperatures that would be considered unusual at any location in Australia would be those in the highest (or lowest) 10 per cent of temperatures experienced at that location over time.
“In recent years there has been a tendency for summer-like temperatures to continue beyond the end of February into March (and even into April) in many parts of Australia,” she said.
“This is due to the effects of global heating on weather patterns.”
On February 15th, the BOM forecast predicts an 80% chance of higher than average temperatures for most of Australia. Credit: Source: Bureau of Meteorology
Will it rain in autumn, and is El Niño still here?
The forecast for March to May signals below-average rainfall for parts of the north, including northern Queensland.
BoM senior hydrologist Dr Masoud Edraki said this outlook encompasses part of the wet season, including the tropical cyclone season, with significant rainfall still a possibility.
“Forecast for other areas does not show a clear signal for either being below or above normal rainfall during March to May,” Edraki said.
Last September, Australia’s weather bureau formally , and while it continues, the Pacific is expected to return to neutral during autumn.
“El Niño has its biggest effect on Australia in spring,” King explained.
“Looking at the forecasts for late summer and early autumn, the El Niño effect is still there a little bit, but it’s weaker. It’s not as big an influence, and it does mean that there’s a slightly decreased chance of wet conditions, but it’s a pretty mild effect.”
Lindesay said the full heating impact of an El Niño event on air temperatures is usually felt in the year after the start of the event.
“We expect the now-weakening El Niño event to have contributed to higher than normal air temperatures since mid-2023, and to continue to contribute to higher than normal air temperatures.
Is extreme weather on the horizon?
Lindesay said extreme weather events, such as severe storms and floods, are more likely to occur when rainfall-producing weather systems take place under conditions of higher temperatures and humidity because of the additional energy in the atmosphere.
“Given that the seasonal outlook is for average to drier than average conditions through autumn, the frequency of extreme storms may decline in coming months,” she said.
“However, when storms do occur, they could have severe storm characteristics due to the excess heat available.”
King said there is a higher probability of heatwaves.
“We are now in late summer and we are more likely to experience more heat waves across some parts of the continent. Additionally, there could be a risk of extreme heat events in early autumn,” he said.
Will warmer autumns become the new norm?
While we will always have a range of climate conditions, King said, we can’t deny a warming trend.
“We’re seeing more warm seasons and more frequent and more intense heatwaves as well,” he said.
“So, in general, we should expect to see more and more of these kinds of events.
“We will still have cold spells in the future as well. It’s just that they’ll be less frequent and less intense.”
Lindesay said every month since April/May 2023, the global monthly average sea surface temperatures have been the highest on record since 1979.
Similarly, the global average air temperatures have been the highest on record for every month since June 2023, which includes January 2024.
2023 was recorded as the hottest year on record globally.
“Warmer autumns are likely to continue in future as the length of the hottest season of the year (summer) extends,” Lindesay said.
“This does not mean that there will be no cooler autumns, just that the balance is tipped in favour of warmer autumns.”
