Greater Sydney in summer 2020-21: cooler than recent years

Greater Sydney in summer 2020–21 was much cooler than recent summers, with daytime temperatures 1-2 °C below the average of recent decades. Summer rainfall was close to or slightly above average.

Close to average rainfall

  • Rainfall across Greater Sydney in summer 2020–21 was close to or slightly above the average of recent decades.
  • Rainfall was above average in the northermost parts of metropolitan Sydney and on the Central Coast, with the highest summer total of 614.0 mm at Olney Forest near Wyong.
  • December saw above average rainfall across Greater Sydney, particularly some northern suburbs and on the Central Coast, with frequent rain in the second half of the month.
  • Severe thunderstorms affected Greater Sydney on 1 December, with power outages and some tree damage in high winds; a gust of 106 km/h was reported at Richmond, the highest of the summer.
  • January rainfall was close to or below average, although a low pressure trough from 27 to 29 January brought 20-100 mm of rain, with the highest falls on the Central Coast.
  • February rainfall was close to average, with thunderstorms and showers bringing 20-40 mm of rain several times during the month.

Cooler than recent summers

  • Daytime temperatures across Greater Sydney in summer 2020–21 were 1-2 °C below the average of recent decades.
  • In contrast, summers in recent years have seen daytime temperatures 1-3 °C above the average.
  • Days were generally mild throughout, with only a few periods in December and January reaching into the 30s.
  • A stationary high pressure system in the Tasman Sea combined with an inland trough brought very hot air over the Sydney Basin from 22 to 26 January.
  • Temperatures were around 6 to 10 °C above the January average during this period, although no records were set.
  • Night-time temperatures were generally within 1 °C of average in December and February, and around 1 °C below average in January.

Sydney (Observatory Hill)

  • Total rainfall for Sydney (Observatory Hill) was 337.4 mm, 13% above the average at the former Observatory Hill site.
  • The mean daily maximum temperature for Sydney (Observatory Hill) was 26.7 °C, 1.0 °C above the average at the former Observatory Hill site.
  • The warmest day was 37.1 °C on 26 January, and the coolest day was on 19 December when the temperature reached 19.6 °C.
  • Sydney (Observatory Hill) recorded 5 consecutive days over 30 °C from 22 to 26 January; only the ninth such instance since records at Observatory Hill began in 1859, but the third year in a row that this has occurred.
  • The mean daily minimum temperature for Sydney (Observatory Hill) was 18.8 °C, 0.4 °C above the average at the former Observatory Hill site and the lowest for summer since 2011–12.
  • The coldest morning was 14.4 °C on 9 December, and the warmest morning was on 24 January when the minimum temperature was 22.2 °C.

Further information

Media
(03) 9669 4057

Extremes in summer 2020-21
Hottest day 41.6 °C at Sydney Airport AMO on 26 Jan 2021
Warmest days on average 28.6 °C at Penrith Lakes AWS
Coolest days on average 22.0 °C at Mount Boyce AWS
Coldest day 12.8 °C at Mount Boyce AWS on 1 Jan 2021
Coldest night 5.0 °C at Mount Boyce AWS on 8 Dec 2020
Coolest nights on average 12.1 °C at Mount Boyce AWS
Warmest nights on average 19.4 °C at Sydney Harbour (Wedding Cake West)
Warmest night 23.2 °C at Cooranbong (Lake Macquarie AWS) on 27 Jan 2021
Warmest on average overall 23.0 °C at Penrith Lakes AWS
Coolest on average overall 17.0 °C at Mount Boyce AWS
Wettest overall 614.0 mm at Wyong (Olney Forest)
Wettest day 105.0 mm at Terrey Hills AWS on 30 Dec 2020
Strongest wind gust 106 km/h at Richmond RAAF on 1 Dec 2020




Summary statistics for summer 2020-21
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2020-21
Diff
from
average
Highest for
summer
2020-21
Mean for
summer
2020-21
Diff
from
average
Lowest for
summer
2020-21
Total for
summer
2020-21
Average
for
summer
Rank of
summer
2020-21
Fraction of
summer
average
Badgerys Creek AWS 28.0 -1.3 40.6 26 Jan 2021 16.3 -0.4 9.9 9 Dec 2020 256.6 238.2 average 108%
Bankstown Airport AWS 27.6 -0.4 40.5 26 Jan 2021 17.8 +0.1 12.4 21 Jan 2021
Camden Airport AWS 27.8 -1.3 39.9 24 Jan 2021 16.3 -0.1 9.0 9 Dec 2020 227.8 242.7 average 94%
Campbelltown (Mount Annan) 27.8 -1.4 40.0 24 Jan 2021 15.9 -0.6 8.9 9 Dec 2020 236.6 236.6 average 100%
Canterbury Racecourse AWS 26.2 -1.1 39.5 26 Jan 2021 17.6 -0.3 11.8 21 Jan 2021 211.8 253.7 average 83%
Cooranbong (Lake Macquarie AWS) 26.4 -1.9 37.8 26 Jan 2021 16.9 -0.2 10.5 17 Jan 2021 481.2 334.0 high 144%
Gosford AWS 25.8   38.7 26 Jan 2021 17.8   12.2 9 Dec 2020 408.6
Holsworthy Aerodrome AWS 26.9   39.6 26 Jan 2021 16.9   10.4 21 Jan 2021 212.0
Holsworthy Defence AWS 26.6   41.2 26 Jan 2021 16.2   10.8 21 Jan 2021 268.2
Horsley Park Equestrian Centre AWS 27.2 -2.0 39.1 26 Jan 2021 16.8 -0.5 11.0 9 Dec 2020 276.0 257.3 average 107%
Mangrove Mountain AWS 25.6 -1.3 37.3 26 Jan 2021 15.9 -0.5 10.0 9 Dec 2020 469.2 334.8 high 140%
Mount Boyce AWS 22.0 -1.4 33.6 1 Dec 2020 12.1 -0.7 5.0 8 Dec 2020 409.4 340.7 high 120%
Norah Head AWS 25.6 -0.2 36.0 26 Jan 2021 19.3 -0.1 15.0 9 Dec 2020 390.0 270.7 high 144%
Parramatta North (Masons Drive) 26.9 -1.2 40.0 26 Jan 2021 16.8 -0.4 11.2 21 Jan 2021 280.8 303.9 average 92%
Penrith Lakes AWS 28.6 -1.6 40.7 26 Jan 2021 17.4 -0.7 11.7 9 Dec 2020 289.0 277.5 average 104%
Richmond RAAF 27.9 -1.7 39.8 26 Jan 2021 17.0 -0.3 10.5 17 Jan 2021 268.6 276.4 average 97%
Springwood (Valley Heights) 25.8 -2.0 37.5 26 Jan 2021 15.8 -0.8 10.9 9 Dec 2020 462.8 368.3 average 126%
Sydney (Observatory Hill) 26.7   37.1 26 Jan 2021 18.8   14.4 9 Dec 2020 337.4
Sydney Airport AMO 26.6 +0.2 41.6 26 Jan 2021 19.0 +0.4 15.0 9 Dec 2020 254.0 280.8 average 90%
Sydney Harbour (Wedding Cake West) 23.7 -0.7 30.9 18 Dec 2020 19.4 -0.6 16.0 8 Dec 2020
Sydney Olympic Park AWS (Archery Centre) 27.0   41.0 26 Jan 2021 18.0   12.8 9 Dec 2020 236.4
Terrey Hills AWS 24.4 -1.8 37.5 26 Jan 2021 17.2 -0.6 12.0 9 Dec 2020 464.4 313.4 high 148%

Notes

The Seasonal climate summary, generally published on the first working day of each month, lists the main features of the weather in Greater Sydney 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 summary includes data from observing sites in or near the Greater Sydney “Greater Capital City Statistical Area” (GCCSA). The Australian Bureau of Statistics designed the GCCSAs to “include the population within the urban area of the city, as well as people who regularly socialise, shop or work within the city, and live in small towns and rural areas surrounding the city. It is important to note that GCCSAs do not define the built up edge of the city. They provide a stable definition for these cities and are designed for the output of a range of social and economic survey data.

This statement has been prepared based on information available at 11 am on Monday 1 March 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 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, 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 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.

Further information

Media
(03) 9669 4057

Climate