Summer 2021-22 was another one for the Tasmanian record books.
Western Tasmania was very dry this summer, with some sites having their driest summer on record including Lake Margaret Power Station with 76 years of record, and King Island Airport with 47 years of record.
It was only parts of north-eastern Tasmania and the Furneaux Group that had near average rainfall for summer, and Gray (Dalmayne Rd) recorded the state’s wettest day this season with 281.8 mm on 7 January.
For Tasmania overall, summer rainfall was 42 per cent below average and the driest since 1980-81, making it the state’s fourth driest summer on record.
The dry summer conditions were caused by persistent high-pressure systems to the south and west of Tasmania, keeping rain from cold fronts away from the state.
These high-pressure systems were associated with a climate driver called the Southern Annular Mode, or the SAM, which was in a positive phase during most of summer.
A positive SAM in summer typically brings below average rainfall to western Tasmania.
Tasmania also recorded its fifth warmest summer, with a mean maximum temperature that was 1.7 degrees Celsius higher than average, and a mean minimum that was 0.92C higher than average.
The drier and warmer than average conditions contributed to a fire in the Franklin-Gordon Wild Rivers National Park in February which burned through at least 300 hectares, threatening a globally significant stand of ancient Huon pines.
December: Dryest since 1994
Summer 2021-2022 began with very dry conditions across most of Tasmania.
December rainfall was 67 per cent below average for Tasmania overall, making it the sixth lowest on record for the state and the driest December since 1994.
Several Tasmanian sites had their driest December on record including Flinders Island Airport, Whitemark Post Office, and Barrington Post Office, all with more than 50 years of records.
Days were warmer than average across the state, except for King Island where maximum temperatures were near average for December.
Overall, the mean maximum temperature for Tasmania was about 1.7C warmer than average.
The mean minimum temperature for Tasmania was close to average, although nights were warmer than usual along the north coast.
Two sites had their lowest December temperature on record on the fifth of the month: Campania (Kinkora) with 1.4C, and Butlers Gorge with a chilly minus 3.3C.
Butlers Gorge also had its coolest nights on average since December 1969, with a mean daily minimum temperature of 4.6C.
Other stand-outs include:
- Warmest on average overall: 17.3C at Launceston (Ti Tree Bend)
- Coolest on average overall: 7.7C at kunanyi (Mount Wellington Pinnacle)
January: Equal warmest on record
The dry start to summer for western Tasmania continued into January, with much of the west coast having monthly rainfall totals in the bottom 10 per cent of January records.
These drier than average conditions in the west saw fires start later in the month that destroyed property and put residents of Tullah on alert for evacuations.
Despite above average rains in the north-east of the state, rainfall for Tasmania overall was 13 per cent below average for January, the driest since 2019.
In terms of summer heat, the mean temperature for Tasmania was 2.51C above average, making it the equal warmest January on record with 2019.
January nights were the warmest on record for Tasmania overall, with a mean minimum temperature of 2.3C above average.
At least 26 sites across the state had their warmest January nights on record.
This included Launceston (Ti Tree Bend), Devonport Airport, King Island Airport, Cape Grim BAPS (Comparison), Wynyard Airport, Bicheno (Council Depot), and St Helens Aerodrome, all of which recorded average minimum temperatures of around 15C for the month .
January days were in the warmest 10 per cent of records for the west and much of the north.
Overall, for Tasmania, the mean maximum temperature was 2.7C above average, the third highest on record and the warmest since January 2019.
Humidity was above average for Tasmania during January, and several sites experienced their warmest January on record, with average monthly temperatures of:
- 20.0C at Flinders Island Airport
- 18.8C at Smithton Aerodrome
- 17.9C at Strahan Aerodrome
February: Dryest in 15 years
Dry conditions returned to much of northern and eastern Tasmania in February, and parts of the south were in the driest 10 per cent of February records, including Hobart.
Hobart Airport had its driest February in 64 years of record, and Hobart (Ellerslie Road) had its driest February since 2001.
Some parts of the north-east had near average rainfall, but elsewhere totals were below average, again including the west.
Overall, Tasmania recorded around half of its typical February rainfall total, making it the driest February since 2007.
Temperatures were warmer than average for much of the state, and the warmest for February since 2016.
Both days and nights were warmer than average for most of the state, but days were closer to average in the east and nights were closer to average in the west.
Tasmania’s mean maximum temperature for February was 0.71C higher than average, and the mean minimum was 0.43C higher than average.
Stand-outs for February include:
- Hottest day: 31.9C at Friendly Beaches on the 1st.
- Warmest days on average: 25.8C at Launceston (Ti Tree Bend)
Autumn rainfall is likely to be above average in eastern and north-eastern Tasmania, and close to average elsewhere around the state.
Both maximum and minimum temperatures are very likely to be above average across Tasmania, partly due to above average ocean temperatures around the state.
Bushfire risk is forecast to be normal for Tasmania.
The La Nia event in the tropical Pacific has peaked and will most likely return to neutral conditions during the autumn.
As La Nia weakens it can continue to have its influence on weather and climate.
La Niña events typically bring above average rainfall to large parts of eastern Australia during autumn, including Tasmania’s north-east.
More information about Tasmania’s weather can be found on the Bureau Of Meteorology’s website.
More climate news can be found on the BOM’s website.
Dr Andrew Marshall is a senior climate researcher at the Bureau of Meteorology in Tasmania