This year saw some of the hottest temperatures ever recorded over a sustained period in the northern hemisphere, with stories of intense rainfall and flood, drought, wildfires and heat-induced illness – even death – abounding.

As Australia followed the devastating international headlines from afar, one question inevitably popped up around water coolers everywhere:

Should we be bracing ourselves for similar conditions in Australia this summer?

The Bureau of Meteorology declared on September 19 that Australia is now in the grip of an El Niño climate pattern. And, according to CEO of the Bureau of Meteorology, Dr Andrew Johnson FTSE FAICD (Bachelor of Agricultural Science (Honours) ’88, Doctor of Philosophy ’92, Master of Public Administration (Harvard)), the probability of higher-than-average temperatures and lower-than-average rainfalls for October–December 2023 is likely for most of Australia.

Contact spoke to Dr Johnson to help you understand what El Niño means and what Australians should expect for the summer ahead.

El Niño – it’s definitely coming

El Niño marks the start of a natural climate phenomenon that will influence weather patterns right across the Pacific. A positive Indian Ocean Dipole (IOD) is also underway. These climate drivers to our east and west strengthen the likelihood of the warm and dry conditions forecast for large parts of Australia over summer.

What’s the difference between El Niño and La Niña?

El Niño and La Niña events are a natural part of the global climate system. They occur when the Pacific Ocean and the atmosphere above it change from their neutral ('normal') state for several seasons.

El Niño events are associated with a warming of the central and eastern tropical Pacific, while La Niña events are the reverse, with a sustained cooling of these same areas. So, fire is often associated with El Niño and flood with La Niña.

Should we be concerned about El Niño?

A significant risk during El Niño years is heatwave. What is not well known is that heatwave kills more Australians each year than all other natural hazards combined, and those most impacted are often the most vulnerable members of our society.

“We can very accurately forecast extreme heat many days in advance, so we ask the community to be well prepared and to look out for family, friends or neighbours who might be at risk,” Dr Johnson said.

“With the last 3 very wet La Niña summers, vegetation has also flourished throughout the country, providing an abundant fuel source as it dries out.

“Bushfire activity varies across Australia with the changes in seasonal weather patterns and with less rain and hotter temperatures, the likelihood of them occurring is higher.

“And wind, temperature, humidity and terrain can all affect bushfire behaviour, with many other local factors amplifying their size and severity.”

In Queensland, peak bushfire season is July–October, but with hot, dry conditions this could extend for longer.

Does being in the southern hemisphere help?

Landmass heats and cools more quickly compared with a large body of water like an ocean. So, it comes as no surprise to learn that summer in the northern hemisphere (with twice the land mass) is generally warmer than summer in the southern hemisphere.

In Australia, maximum temperatures are often associated with heat moving south from the north and centre of the continent. An El Niño and positive IOD will likely be the biggest factor in spring and summer in Australia this year.

Image: mbruxelle/Adobe Stock

Will summer 2023 be Australia’s hottest ever?

Australia has just recorded its warmest winter on record. It was also the warmest winter for Queensland, New South Wales and Tasmania, and the second warmest for Victoria and South Australia.

The national mean temperature was 1.53°C above the long-term average for winter and the warmest on record since national observations began in 1910, exceeding the previous record of 1.46°C above average set in 1996.

In the northern hemisphere, the 2023 summer was also the warmest on record, and oceans globally have been the warmest on record each month for the last 5 months (April–August 2023).

According to Dr Johnson, although we cannot yet predict whether 2023 will be Australia's hottest summer, the forecast for spring and summer is clear.

“With the influence of climate change, warm oceans everywhere and both a positive IOD and El Niño, the risk of drier conditions and above average temperatures is high,” he said.

Which parts of Australia will be most affected by extreme weather conditions?

In the coming decades, Australia can expect to experience a continued increase in air temperatures, with more heat and fewer cold extremes. We may also see less snow, fewer – but more intense – cyclones, and less rain in the southern and eastern parts of the country.

“This will likely lead to more time in drought and a higher number of dangerous fire weather days during a longer fire season for southern and eastern Australia,” Dr Johnson said.

“Conversely, we may also see more intense heavy rainfall events around the country, leading to flash flooding.

“In the northern part of Australia, more frequent and severe bleaching events in coral reefs may arise from increased and longer-lasting marine heatwaves as well.”

Are volatile summers something we just have to get used to in the future?

According to the State of the Climate 2022 report, the past decade has seen record-breaking extremes leading to natural disasters, all exacerbated by human-caused climate change.

“Our observations indicate ongoing, long-term climate change interacting with underlying natural variability,” Dr Johnson said.

“The associated changes in weather and climate extremes – such as extreme heat, heavy rainfall and coastal inundation, fire weather and drought – have a large impact on the health and wellbeing of our communities and ecosystems and are happening at an increased pace, impacting the lives and livelihoods of all Australians.

“We need to plan for, and adapt to, the changing nature of climate risk now and in the decades ahead.

“The severity of impacts on Australians and our environment will depend on the speed at which global greenhouse gas emissions can be reduced.”

Preparing for bushfire season

Clear gutters and roof of leaves, twigs, bark and other debris. Consider installing gutter guards.
Enclose open areas under decks and floors.
Install steel wire mesh screens on windows, doors, vents and weep holes.
Point LPG cylinder relief valves away from your house.
Check and maintain firefighting pumps, generators and water systems.
Seal gaps in external roof and cladding.
Remove flammable items away from your home (such as woodpiles, mulch, boxes, hanging baskets and outdoor furniture).
Reduce vegetation along access paths.
Mow your lawn regularly.
Remove excess flammable materials such as long dry grass, dead leaves and branches.
Trim low-lying branches around your home to a height of 2 metres from the ground.

Source: Queensland Fire and Emergency Services – Prepare for bushfire season.

Lightning Round, with Dr Andrew Johnson

When it comes to understanding the weather, there's no such thing as a stupid question. Dr Johnson answered some of the burning questions we've been chasing answers to for years.

Q. Can lightning strike twice in the same place?

A. Yes, it can happen within the same storm or many years apart. We know this because lightning strikes emit a range of electromagnetic radiation, including visible light and radio waves, which the Bureau of Meteorology monitors in real-time to pinpoint their location.

Q. Does thunder occur when 2 clouds collide?

A. No, a thunderstorm is essentially a cloud that produces lightning. The lightning is a gigantic spark created when an enormous imbalance of positive and negative charge occurs. It greatly heats the surrounding air to many thousands of degrees, causing the air to expand violently, resulting in the crashing noise known as thunder.

Q. ‘It came without warning’: can a major storm event be unforeseen?

A. It is possible, especially in the case of isolated thunderstorm activity, that some thunderstorms, and/or strong winds will not be detected and reported to the Bureau.

Q. Do weather apps actually work?

A. While I can’t vouch for commercial apps, I can recommend the BoM Weather app for access to hourly and 7-day forecasts, rain radar and warnings – wherever you are. The app includes past and current weather happenings; hourly and 7-day weather forecasts; coastal forecasts and tide times; rain maps; and warning notifications for fire weather, flood, heatwave, marine wind, severe thunderstorm, severe weather, tropical cyclone and tsunami.

Q. What does the ‘percentage of rain’ really mean on a weather forecast?

A. This figure shows the percentage within the area being monitored that will definitely see rain. It’s not necessarily the chance that rain will happen, but probably amounts to the same thing: the higher the percentage, the more likely rain will be to happen.

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It's official: El Niño is here