Remote Islands and Antarctica in September 2025

Australia's Indian Ocean islands

  • The monthly rainfall total at Christmas Island Aero was 4.6 mm, this was below the September average rainfall of 54.8 mm.
  • At Christmas Island Aero, the mean maximum temperature was 0.4 °C above average and the mean minimum temperature was 0.9 °C above average.
  • The monthly rainfall total at Cocos Island Airport was 138.2 mm, this was 153% of the average September rainfall for the station of 90.2 mm.
  • At Cocos Island Airport, the mean maximum temperature was 0.3 °C above average and the mean minimum temperature was 0.6 °C above average.

Australia's Pacific Ocean islands

  • Norfolk Island Aero recorded a monthly rainfall total of 81.8 mm, this was below the average September rainfall of 92.3 mm.
  • At Norfolk Island Aero, the mean maximum temperature was 1.0 °C above average and the mean minimum temperature was 0.8 °C above average.
  • The monthly rainfall total at Lord Howe Island Aero was 29.0 mm, this was the lowest September rainfall on record for the station. The average September rainfall is 113.1 mm.
  • At Lord Howe Island Aero, the mean maximum temperature was 1.1 °C above average and the mean minimum temperature was 0.6 °C above average.

Australia's Antarctic and sub-Antarctic territories

  • The strongest wind gust recorded at the Australian Antarctic stations during September was 172 km/h at Casey on the evening of the 17th.
  • Mean maximum and mean minimum temperatures for September were above average at Davis and Mawson, and below average at Casey.
  • Monthly precipitation at Macquarie Island was 101.2 mm, this was above the September average rainfall of 77.1 mm.
  • At Macquarie Island, the mean maximum and minimum temperatures were 0.2 °C and 1.1 °C below average, respectively.
  • The strongest wind gust recorded in September at Macquarie Island was 104 km/h on the morning of the 30th.

Highest September total rainfall for at least 20 years
Observed
(mm)
Most recent
higher
Average for
September
Casey 41.0 49.2 in 1997 18.9

note: there may be gaps in the historical record at some sites, so it is possible more recent higher values have gone unreported





Summary statistics for September 2025
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
September
2025
Diff
from
average
Highest for
September
2025
Mean for
September
2025
Diff
from
average
Lowest for
September
2025
Total for
September
2025
Average
for
September
Rank of
September
2025
Fraction of
September
average
Offshore Islands
Lord Howe Island Aero 21.1 +1.1 24.0 30th 15.3 +0.6 9.1 15th 29.0 113.1 lowest 26%
Norfolk Island Aero 20.1 +1.0 22.9 30th 14.6 +0.8 11.6 10th 81.8 92.3 average 89%
Christmas Island Aero 26.7 +0.4 28.3 25th 23.2 +0.9 21.3 8th 4.6 54.8 low 8%
Cocos Island Airport 28.6 +0.3 30.0 25th 24.6 +0.6 22.4 19th 138.2 90.2 high 153%
Antarctica and Macquarie Island
Casey -11.2 -1.4 -4.2 22nd -18.9 -1.5 -25.2 27th 41.0 18.1 high 226%
Davis -10.1 +2.6 -2.2 28th -17.1 +2.5 -26.2 1st 0.8 5.4 v low 15%
Macquarie Island 5.2 -0.2 7.2 8th 0.5 -1.1 -4.3 10th 101.2 77.1 high 131%
Mawson -10.4 +3.7 -2.3 29th -17.4 +3.0 -24.0 1st

Daily maximum temperatures for September 2025
Offshore Islands 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Lord Howe Island Aero 18.8 19.9 21.1 21.7 21.2 18.0 19.1 20.7 21.9 22.8 21.5 19.0 20.0 20.6 20.8 22.4 22.7 20.7 21.2 20.8 21.1 21.9 20.3 19.6 21.1 22.4 22.8 23.6 22.4 24.0
Norfolk Island Aero 18.8 18.9 19.1 19.1 19.6 18.1 17.3 17.9 18.7 20.2 21.6 19.8 19.4 19.7 19.3 19.3 20.6 21.4 20.1 20.3 21.4 21.3 20.5 20.5 20.1 21.7 21.4 21.2 22.0 22.9
Christmas Island Aero 25.9 26.8 25.7 26.7 26.8 26.9 23.6 26.0 26.0 26.6 27.1 26.9 27.2 26.6 27.2 26.9 27.3 26.9 27.3 26.7 25.7 27.3 27.4 27.3 28.3 27.4 27.5 26.4 26.2 27.6
Cocos Island Airport 29.2 29.5 29.3 29.4 27.4 27.7 27.2 28.3 28.3 28.5 28.3 29.3 27.2 29.3 29.0 29.0 28.4 27.8 27.5 28.7 28.0 28.6 28.9 29.6 30.0 28.8 28.6 28.9 29.2
Antarctica and Macquarie Island 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Casey -9.3 -11.3 -14.6 -14.8 -7.3 -10.5 -13.4 -6.4 -5.4 -9.6 -9.9 -13.3 -14.1 -14.5 -17.0 -7.0 -5.4 -8.3 -12.1 -16.1 -7.2 -4.2 -9.5 -14.3 -14.3 -13.9 -20.4 -14.2 -8.0 -10.9
Davis -13.0 -9.6 -10.6 -5.8 -5.1 -7.1 -4.3 -6.5 -5.8 -9.8 -10.3 -13.6 -16.1 -15.6 -13.3 -12.1 -13.4 -6.6 -6.2 -8.7 -14.3 -18.2 -17.1 -14.2 -17.4 -13.7 -6.0 -2.2 -2.6 -4.4
Macquarie Island 3.3 6.5 6.9 5.1 4.5 4.0 6.5 7.2 5.2 4.1 5.2 4.1 5.6 6.3 3.0 6.5 6.1 5.6 6.1 6.9 6.1 5.1 5.9 6.0 3.6 5.1 6.0 5.2 3.7 1.7
Mawson -14.6 -11.4 -10.3 -8.0 -9.4 -9.1 -6.7 -4.6 -5.3 -9.2 -14.3 -13.0 -12.0 -11.9 -11.1 -12.7 -17.7 -10.4 -7.8 -6.7 -13.3 -15.0 -16.1 -15.3 -16.2 -15.4 -7.3 -3.1 -2.3 -3.1
Values are the maximum temperature, usually in the 24 hours from 9 am on the day indicated,
and typically occurred in the afternoon of that day.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily minimum temperatures for September 2025
Offshore Islands 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Lord Howe Island Aero 11.3 10.5 16.0 15.6 14.0 15.1 13.5 13.6 16.9 19.3 18.7 14.5 11.3 11.6 9.1 13.8 17.7 16.6 17.5 17.2 12.8 16.3 14.3 13.8 16.5 16.8 19.0 18.5 17.3 19.3
Norfolk Island Aero 13.9 11.6 12.5 15.5 16.8 16.5 13.5 13.7 12.3 11.6 16.8 15.1 14.8 13.5 13.9 13.3 13.3 16.6 15.1 13.4 17.3 15.3 14.5 14.4 15.6 14.9 15.2 13.8 15.4 17.2
Christmas Island Aero 23.4 23.3 23.8 23.6 23.2 23.0 21.6 21.3 22.8 23.1 22.8 22.5 23.4 23.4 23.2 23.1 23.2 23.2 23.2 23.3 23.6 23.4 23.2 23.2 22.8 23.5 23.9 24.1 24.0 23.7
Cocos Island Airport 24.5 25.6 25.9 26.2 24.2 24.5 24.0 23.3 25.2 24.3 24.1 23.5 23.5 24.5 24.5 25.9 24.2 25.0 22.4 24.2 24.2 25.4 24.6 25.8 25.6 25.4 23.6 22.7 23.6
Antarctica and Macquarie Island 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Casey -11.3 -16.5 -17.8 -18.0 -24.0 -16.1 -14.2 -24.3 -22.1 -13.8 -15.8 -16.9 -18.7 -16.7 -22.4 -24.8 -20.3 -12.7 -17.7 -21.7 -23.7 -20.1 -17.6 -16.6 -19.7 -16.9 -25.2 -24.6 -20.8 -15.7
Davis -26.2 -25.2 -13.5 -17.8 -14.9 -8.8 -8.7 -7.9 -8.4 -14.9 -14.5 -19.9 -23.1 -21.0 -20.0 -17.0 -23.1 -21.8 -13.5 -14.5 -18.9 -23.0 -22.9 -21.5 -23.0 -21.1 -19.3 -13.8 -7.9 -6.6
Macquarie Island -1.7 0.6 3.2 2.6 0.2 0.4 0.8 2.5 4.3 -4.3 -2.9 -0.5 -0.4 0.1 3.0 -0.6 0.4 -2.9 0.9 3.7 1.9 1.4 0.3 3.2 1.1 -1.1 0.8 3.9 -1.0 -3.7
Mawson -24.0 -23.6 -15.8 -14.6 -16.0 -19.1 -16.6 -10.5 -9.1 -11.0 -20.5 -20.0 -18.2 -13.9 -15.5 -19.1 -23.4 -22.7 -19.1 -11.5 -18.4 -19.0 -21.3 -22.6 -21.9 -21.0 -20.6 -15.8 -9.9 -6.1
Values are the minimum temperature, usually in the 24 hours to 9 am on the day indicated,
and typically occurred that morning.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily rainfall for September 2025
Offshore Islands 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Lord Howe Island (Milky Way) 0.4 1.2 - 0.2 0.2 - - - - - 1.0 1.4 0.6 0.6 0.4 - - 2.6 - - 11.2 - 9.0 8.8 - - - - - 0.2
Lord Howe Island Aero - - - 0.6 0.2 - - - - - 0.6 1.0 0.2 - - - - 8.2 - - 10.8 - 0.8 5.8 0.2 - - - - 0.6
Norfolk Island Aero 0.2 - - - 5.6 9.4 - - - - - 3.4 0.2 0.2 - 0.4 - - 0.4 - - 60.8 1.2 - - - - - - -
Christmas Island Aero - - - - - - 1.2 2.6 - - 0.4 - - - - - - - - - - - 0.2 - - - - - - 0.2
Cocos Island Airport - 1.6 1.0 - 1.0 2.0 1.2 1.4 - 0.6 1.6 12.6 66.8 8.8 6.2 - 4.2 - 4.0 0.2 - - 5.6 - - - 1.6 17.6 0.2 -
Antarctica and Macquarie Island 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Casey 0.8 5.4 - - - 5.0 0.2 - - 9.8 1.0 0.2 - 0.6 0.6 - 2.6 4.4 - - - - - - - - - - - 10.4
Davis - - - - - - - - - - - - - - - - - - - - 0.8 - - -
Macquarie Island 4.4 1.0 0.6 4.4 1.2 5.8 4.4 0.6 1.2 0.6 5.6 14.4 2.2 5.6 1.4 0.2 9.8 0.2 1.0 1.2 4.6 0.6 6.4 3.8 2.4 2.2 1.8 8.2 2.6 2.8
Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with → are part of a longer accumulation, which is shown on the final day.
Values over 100 mm have been rounded to the nearest whole millimetre.
Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
Rainfalls coloured
according to the amount
0 1.0 5.0 10.0 15.0 25.0 50.0 100 150 200 300 400 600 millimetres

Map of the areas covered by this summary

Notes

The Monthly climate summary, usually published in the first week of the following month, lists the main features of the weather in Remote Islands and Antarctica using the most timely and accurate information available on the date of publication; it will generally not be updated.

This statement has been prepared based on information available on Monday 13 October 2025. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

In some situations, some or all of the rainfall is in the form of hail or snow. In these cases, the totals given are for the water equivalent: the depth of liquid water that results from melting any frozen precipitation. There can be significant 'undercatch' of snow in strong winds, meaning the true precipitation can be higher than that reported.

Averages for individual sites are long-term means based on observations from all available years of record, excluding the current year. The length of record can vary widely from site to site. Averages are not shown for sites with fewer than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Where temperature area averages are mentioned, they are derived from the ACORN-SAT dataset.

Information about Australian Indigenous seasonal calendars is available at the Indigenous Weather Knowledge website.

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