Remote Islands and Antarctica in September 2021

Australia's Indian Ocean islands

  • Christmas Island Aero recorded 63.0 mm of rainfall during the month, which was above the long-term September average of 53.5 mm.
  • In contrast, Cocos Islands Airport had a monthly rainfall total of just 17.0 mm, well below the September average of 91.3 mm.
  • Mean minimum temperatures were warmer than average at both Christmas Island Aero and Cocos Island Airport, 1.5 °C and 0.8 °C above average respectively.
  • Mean maximum temperatures were within half a degree above average at both islands.

Australia's Pacific Ocean islands

  • Lord Howe Island Aero's rainfall for the month of 138.8 mm was 24% above its September average; more than 70 mm of rainfall fell on two days (the 15th and 22nd), contributing to about a half of the rainfall total for this month.
  • Both mean maximum and mean minimum temperatures were close to average at Lord Howe Island Airport.
  • Rainfall total for the month at Norfolk Island Aero was three quarters of September average. During the month, rainfall was recorded on 21 days, however there were only 8 days with rainfall that exceeded 2 mm.
  • At Norfolk Island Aero, both mean maximum and mean minimum temperatures were warmer than average.

Australia's Antarctic and sub-Antarctic territories

  • The strongest wind gust recorded during the month was 174 km/h at Casey station on the 14th and at Mawson station on the 25th.
  • Total monthly wind run was above average at Mawson and Davis, but below average at Casey; Mawson's total wind run was the highest in September since 2015.
  • The coldest temperature recorded during the month was −28.2 °C at Davis station on the 6th.
  • Both mean daytime and night-time temperatures were above average at each of the Australian Antarctic stations.
  • Mawson station recorded a maximum temperature of 0.7 °C on the 5th, its highest September temperature on record.
  • Casey station recorded a minimum temperature of −1.7 °C on the 1st, its warmest September night on record.
  • Precipitation at Macquarie Island was recorded on most days of the month, and total precipitation was 29% above the September average.
  • At Macquarie Island, after a warmer than average start to the month, a mixture of cooler and warmer days resulted in mean maximum temperature that equalled the September long-term average..
  • Macquarie Island's mean minimum temperature was slightly cooler than average.
  • The strongest wind gust recorded at Macquarie Island this month was 139 km/h on the 7th, the strongest for September since 2014.

Further information

Media
(03) 9669 4057

Record highest September temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Mawson 0.7 on the 5th -0.6 on the 13th in 1996 68 -14.2



Record highest September daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Casey -1.7 on the 1st -2.2 on the 19th in 2013 33 -17.4



Summary statistics for September 2021
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Precipitation
(millimetres)
Mean for
September
2021
Diff
from
average
Highest for
September
2021
Mean for
September
2021
Diff
from
average
Lowest for
September
2021
Total for
September
2021
Average
for
September
Rank of
September
2021
Fraction of
September
average
Offshore Islands (district 200)
Christmas Island Aero 26.6 +0.3 27.9 28th 23.1 +0.8 21.7 4th 63.0 53.5 high 118%
Cocos Island Airport 28.7 +0.5 29.8 7th 25.4 +1.5 23.5 3rd 17.0 91.3 low 19%
Lord Howe Island Aero 19.9 -0.1 22.9 25th 14.5 -0.2 8.8 1st 138.8 111.6 high 124%
Norfolk Island Aero 19.6 +0.5 22.2 14th 14.5 +0.7 12.1 12th 69.6 92.5 average 75%
Antarctica and Macquarie Is. (district 300)
Casey -9.4 +0.5 2.1 1st -16.1 +1.3 -27.2 26th 32.6 17.9 high 182%
Davis -10.4 +2.4 -2.9 14th -18.0 +1.8 -28.2 6th 11.6 5.7 high 204%
Macquarie Island 5.4 0.0 7.8 2nd 1.2 -0.4 -2.5 13th 97.8 75.8 high 129%
Mawson -11.0 +3.2 0.7 5th -17.4 +3.1 -26.0 24th
Note: Precipitation values from Casey and Davis should be used with caution.

Daily maximum temperatures for September 2021
Offshore Islands (200)123456789101112131415161718192021222324252627282930
Christmas Island Aero27.127.427.026.627.027.027.527.326.326.926.525.024.524.924.725.025.425.326.426.527.227.727.327.526.926.327.927.627.4
Cocos Island Airport28.829.128.627.928.429.329.829.028.928.628.828.028.328.528.028.028.627.728.728.628.929.129.429.128.928.929.128.929.2
Lord Howe Island Aero20.019.720.020.220.719.118.018.620.222.021.422.022.319.617.218.219.119.820.522.519.018.619.521.322.918.617.818.820.020.5
Norfolk Island Aero18.919.018.619.120.120.019.518.819.019.518.818.720.822.220.520.218.618.219.320.221.022.018.520.421.021.618.617.718.018.6
Antarctica and Macquarie Is. (300)123456789101112131415161718192021222324252627282930
Casey2.1-2.3-2.9-2.2-7.4-10.4-8.2-13.9-9.0-11.4-5.9-6.5-6.6-2.1-1.5-4.9-6.7-8.4-14.8-12.4-13.0-13.7-12.6-12.7-12.2-16.8-15.8-18.8-14.9-15.8
Davis-7.1-6.2-13.0-12.9-18.4-17.3-17.0-13.1-11.0-8.9-5.7-8.6-3.9-2.9-3.2-4.5-7.4-9.3-10.5-12.5-14.0-16.1-13.3-13.2-9.3-9.3-9.7-12.5-16.1-5.8
Macquarie Island6.77.87.25.65.25.14.71.82.40.75.76.75.25.94.95.84.96.16.36.65.56.25.45.25.16.16.94.95.35.8
Mawson-9.1-8.7-12.1-8.50.7-3.5-10.6-13.2-11.2-10.3-12.7-9.7-11.3-9.2-6.7-7.7-6.5-10.7-12.5-12.1-15.5-17.7-19.0-17.7-10.1-10.7-12.5-13.2-16.9
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 2021
Offshore Islands (200)123456789101112131415161718192021222324252627282930
Christmas Island Aero23.423.422.621.723.323.723.523.823.422.821.921.922.822.422.322.522.622.722.423.123.323.524.424.223.523.624.023.923.523.0
Cocos Island Airport25.026.023.523.625.626.026.324.126.125.425.524.625.524.824.825.425.825.125.125.824.926.025.626.025.726.026.226.126.0
Lord Howe Island Aero8.815.516.016.717.214.412.514.613.417.010.017.119.216.814.213.114.19.517.29.217.212.513.016.018.116.112.112.715.316.9
Norfolk Island Aero14.015.014.514.516.015.614.514.514.614.115.512.113.017.417.516.114.813.512.613.014.117.414.014.413.416.115.713.112.612.6
Antarctica and Macquarie Is. (300)123456789101112131415161718192021222324252627282930
Casey-1.7-7.9-11.2-11.2-10.3-12.6-19.1-18.0-20.9-18.4-19.4-13.4-14.5-17.6-7.0-5.9-8.8-10.7-19.1-20.1-16.4-17.1-16.0-23.3-16.6-27.2-26.7-22.2-26.7-22.4
Davis-23.8-22.1-13.5-17.0-26.1-28.2-25.3-21.6-20.0-21.0-15.2-11.4-12.1-8.8-7.3-7.6-9.8-13.7-15.1-19.2-19.1-20.5-20.9-18.7-25.5-22.3-13.7-17.2-20.2-24.3
Macquarie Island5.34.75.83.51.31.32.1-1.2-0.3-1.6-1.70.5-2.5-1.03.1-0.32.12.34.34.5-0.71.81.4-0.9-1.5-1.23.70.5-0.3-0.3
Mawson-16.3-12.3-17.2-16.7-16.8-11.4-13.5-20.3-19.2-16.7-16.8-19.1-16.4-14.4-15.2-10.8-10.0-12.0-17.7-18.1-19.6-22.3-22.1-26.0-24.6-18.6-15.9-21.1-20.9-19.6
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 precipitation for September 2021
Offshore Islands (200)123456789101112131415161718192021222324252627282930
Christmas Island Aero - - 0.2 0.4 0.2 0.2 - - - 1.6 18.2 0.2 3.2 15.6 8.6 8.0 5.8 0.4 0.4 - - - - - - - - - -
Cocos Island Airport 3.4 - 8.2 3.4
- - -
0.2
- 0.4 - 0.2 0.2 - - - -
0.2 - 0.6 0.2 - - -
-
Lord Howe Island (Milky Way) - - 0.2 - 0.4 20.0 14.0 0.4 - - - - - 8.4 31.8 4.0 0.6 - 3.0 - 12.8 32.6 2.0 - - - 1.0 - - -
Lord Howe Island Aero - - 0.4 - 0.2 27.0 10.4 - 0.2 - - - - 1.6 39.8 5.4 1.6 - 1.8 0.2 13.6 32.6 2.0 0.2 - - 1.6 0.2 - -
Norfolk Island Aero 1.2 0.2 1.4 10.2 2.2 - 6.0 0.4 0.4 - 2.0 0.2 - 0.2 0.2 14.8 0.6 12.8 - - - 2.4 8.2 0.4 - 0.2 5.0 0.6 - -
Antarctica and Macquarie Is. (300)123456789101112131415161718192021222324252627282930
Casey - - - - - 0.4 0.2 2.0 - 9.8 0.2 0.2 0.8 - 0.4 1.0 - 0.2 - 0.8 9.8 3.6 0.2 - 2.2 - - - - 0.8
Davis - -
0.8 1.0 - - - -

5.0 0.1 - - - - - - - - - - 2.6 0.3 1.6
0.2 - -
Macquarie Island 5.4 - 3.6 0.8 3.2 14.4 7.2 2.4 7.2 11.6 - 0.2 0.8 - 0.4 1.0 - 0.2 2.6 3.8 1.0 3.0 3.0 2.8 8.6 1.8 1.0 2.4 5.6 3.8
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 precipitation report of zero; days left blank have no precipitation report (which often indicates no precipitation fell).
Precipitations 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, generally published on the first working day of each 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. More extensive discussion of significant weather events, along with later information and data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review.

This statement has been prepared based on information available at 4 pm on Friday 1 October 2021. 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 precipitation 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, which vary widely from site to site. They are not shown for sites with less 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 precipitation.

The Rank indicates how precipitation this time compares with the climate record for the site, based on the decile ranking (very low precipitation 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 precipitation 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.

Further information

Media
(03) 9669 4057

Climate