Australia will be hotter and drier than normal this spring and summer as a weak El Niño pattern develops across the Pacific Ocean.
This will be in stark contrast to the past two years, which were dominated by La Niña conditions that contributed to heavy rainfall and cooler temperatures across much of the country, Weatherzone meteorologist Josh Fisher said.
This year's El Niño will also combine with a phenomenon known as the "Indian Ocean Dipole" (IOD). During the next few months, we are expected to experience a drier phase of the IOD as a result of cooler waters off the north-west coast of Australia. The drier phase, combined with weakening easterly trade winds across the tropical Pacific, will lead to lower moisture levels over much of the country and warmer daytime temperatures.
Temperatures this spring and summer are expected to be near average or warmer for all capital cities - and are also likely to be warmer than temperatures in the past two years. These warmer days also come with in an increased risk of heatwaves, particularly for the southern capitals of Adelaide, Melbourne and Canberra.
While heatwaves in Sydney are rarer, they cannot be ruled out. The city experienced an unexpected heatwave in February 2011, a strong La Niña year, which is usually associated with cooler conditions.
Bushfire risk will be higher this season, exacerbated by increased vegetation growth following two years of wet weather. Southern states are at greatest risk due to the prevalence of stronger winds in summer.
Another feature of the warm season is thunderstorm activity. Widespread storms have already battered eastern Australia in the past week.
Quantifying the thunderstorms that we will see is difficult as the correlation to long-term climate drivers (such as El Niño) is low. Storm activity is more dependent on short-range weather patterns.
However, there is an elevated risk of severe thunderstorms, particularly in eastern Australia, due to expectations of high surface temperatures and moderate moisture levels. Compared to the past two years, there is an increased risk of large hail with storms. Localised flash-flooding remains a risk, but we are not likely to see the widespread flooding of the past two years.
Current indications show that tropical cyclone activity will be near-normal for the Australian region this season. While El Niño years typically produce lower cyclone activity over this region, the upcoming El Niño is not expected to be strong and is not expected to have a large impact on the number of cyclones.
Sydney weather statistics can be seen here.
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