Welcome to the Climate and Water Outlook for summer 2021-22. With La Niña now underway, summer
could be wetter than normal across eastern parts of the country. But first, let's
look at recent conditions. Spring has been wetter than normal, with much of the rain
falling in October and November. Some regions have recorded more than three times their normal November rainfall.
The Wide Bay-Burnett region in Queensland also received above
average rain, easing the long-term drought after having missed out on the La Niña rains last summer.
Spring days were very much warmer than average for much of northern Australia, with record
temperatures across the Top End. Darwin had three days in a row over 36 degrees,
the first such sequence in November on record. In contrast, maximum temperatures across
southern Australia were the coolest since 2016.
With above average spring rainfall, soil moisture in the top metre is very much above average
across much of Australia. This has increased runoff with recent rains, contributing to
flooding in some areas of the country. It also means most water storage levels are
higher across eastern Australia and the South West Coast, compared to this time in 2020.
One exception is in south-east Queensland, where total water storage levels remain similar
to last year. So, what will influence our climate in the coming months? In the Pacific
Ocean, La Niña is now established for the second year in a row, with cooler than
normal water in the central and eastern Pacific and warmer waters near Australia. This pattern
is likely to continue until at least the end of January. La Niña typically increases
the likelihood of above average rainfall over summer across much of northern and eastern Australia.
In the Indian Ocean, the negative Indian Ocean
Dipole pattern of warmer waters near Indonesia and cooler waters off Africa has influenced
our climate for much of winter and spring, but it's now approaching its end. Warmer
waters may persist to the north-west of Australia which may to increase the chance of rainfall at times.
To the south, very strong winds over Antarctica helped draw weather systems further
south in October and November, adding to the wetter conditions in New South Wales and Victoria.
This pattern, called the Southern Annular Mode, is likely to remain in place during
December. So, what does this mean for the summer outlook? La Niña is likely to bring
wetter than average conditions across parts of eastern Australia, with highest chance
of above average rainfall in eastern Queensland. The streamflow outlook for November to January
suggests high flows are likely in streams and rivers at most locations. These high
streamflows and forecast above-average rainfall for already saturated catchments, means there
is an increased risk of widespread flooding. Summer days are likely to be warmer than average
across most of Australia, except in parts of the south-east. Minimum temperatures
are likely to be above average across most of the country, so we're all in for some warmer
nights. A wetter forecast and observed conditions means normal to below normal
fire potential in many forested areas east of the great divide. However, areas that have
seen increased grass and crop growth over spring may see that dry out during summer,
increasing the grassfire risk. Of course, bushfires happen every summer in Australia, and even
short periods of hot and windy weather will increase the bushfire risk, so keep an eye
on the Bureau's forecasts and warnings. La Niña also means we are expecting an average
to above average numbers of tropical cyclones and tropical lows. We've already seen our
first tropical cyclone of the season, roughly three weeks earlier than normal. So, in summary,
summer is likely to see: above average rainfall across eastern Australia, warmer than average
days and nights across most of the country, high streamflows at most locations, with an
increased risk of widespread flooding and grassfire risk is raised in areas of New South
Wales and Western Australia. You can find out more about the outlooks on the Bureau's
website. We'll see you next time.