Greater Sydney in winter 2021: Warm days, drier than average

Greater Sydney in winter 2021 saw below average rainfall and warmer than average days.

Dry conditions bolstered by a wet end

  • Although rainfall was above average during August, below-average rainfall for June and July meant winter rainfall was below average.
  • Rainfall was generally 70 to 90% of the long-term seasonal average.
  • Rainfall in June was more consistent, with storms delivering up to 30 mm over the northern suburbs on the 20th and onshore stream shower activity bringing 15 to 30 mm to the eastern suburbs on the 29th.
  • Onshore flow associated with a Tasman Sea low brought 20 to 40 mm of rainfall on the 9th and 10th of July, which was otherwise a mostly dry month.
  • August experienced above average rainfall as a result of a wet two-day period associated with a coastal low where many sites recorded rainfall in excess of their monthly average.

Warm temperatures

  • Temperatures were above their seasonal average, especially during August.
  • In June, daytime temperatures were close to their monthly average while night-time temperatures were below average with many sites being their coolest since the mid-2000s.
  • Some sites had their coldest winter day (lowest maximum temperature) on record as a result of a complex low bringing a large mass of cold air over the state.
  • Temperatures were close to slightly above the monthly average in July.
  • Warmer than average temperatures were experienced in August, with days being particularly warm.
  • Sydney set an August record with 15 consecutive days of 20 °C or above from the 9th to the 23rd.

Sydney (Observatory Hill)

  • Total rainfall for Sydney (Observatory Hill) was 200.2 mm, which is 65% of the long-term average at the former Observatory Hill site, or 67% of the average over recent decades.
  • The mean daily maximum temperature for Sydney (Observatory Hill) was 19.0 °C, which is 1.9 °C above the long-term average at the former Observatory Hill site, or 0.5 °C above the average over recent decades.
  • The warmest day was 25.6 °C on 1 August, and the coolest day was on 10 June when the temperature reached 10.3 °C.
  • The mean daily minimum temperature for Sydney (Observatory Hill) was 9.4 °C, which is 0.6 °C above the long-term average at the former Observatory Hill site, or 0.1 °C below the average over recent decades.
  • The coldest morning was 5.2 °C on 22 July, and the warmest morning was on 1 August when the minimum temperature was 14.9 °C.

Snow and heavy fog during June

  • Moist easterlies and associated rainfall on the 29th and 30th of June led to heavy fog covering Sydney on both mornings, causing major traffic disruptions.
  • The cold outbreak on the 10th of June saw Observatory Hill record its lowest maximum temperature since 1984 (lowest in June since 1899), along with snowfall occuring around the Blue Mountains.

Further information

Media
(03) 9669 4057

Extremes in winter 2021
Hottest day 28.6 °C at Penrith Lakes AWS on 22 Aug
Warmest days on average 19.1 °C at Cooranbong (Lake Macquarie AWS)
Coolest days on average 10.3 °C at Mount Boyce AWS
Coldest day 1.3 °C at Mount Boyce AWS on 10 Jun
Coldest night -2.7 °C at Richmond RAAF on 30 Jul
Coolest nights on average 3.0 °C at Mount Boyce AWS
Warmest nights on average 11.1 °C at Sydney Harbour (Wedding Cake West)
Warmest night 16.3 °C at Norah Head AWS on 23 Aug
16.3 °C at Terrey Hills AWS on 23 Aug
Warmest on average overall 14.4 °C at Norah Head AWS
14.4 °C at Sydney Harbour (Wedding Cake West)
Coolest on average overall 6.6 °C at Mount Boyce AWS
Wettest overall 253.2 mm at Rose Bay (Royal Sydney Golf Club)
Wettest day 56.0 mm at Sans Souci (Public School) on 25 Aug
Strongest wind gust 111 km/h at Wattamolla AWS on 19 Jun

Record lowest winter total rainfall
New record
(mm)
Old
record
Years of
record
Average for
winter
Chatswood Bowling Club 67.0 69.0 in 2002 29 278.6



Record lowest winter daily maximum temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Bankstown Airport AWS 9.6 on 10 Jun = 9.6 on 20 Jul 1983 54 18.1
Camden Airport AWS 8.4 on 10 Jun 9.6 on 20 Jul 1983 45 18.1
Mount Boyce AWS 1.3 on 10 Jun 1.8 on 31 Jul 1994 30 10.3
Richmond RAAF 8.3 on 10 Jun 9.5 on 13 Jul 2011 28 18.5
Badgerys Creek AWS 8.5 on 10 Jun 10.5 on 13 Jul 1997 26 18.2
Canterbury Racecourse AWS 10.2 on 10 Jun 11.3 on 19 Aug 1996 26 18.2
Penrith Lakes AWS 8.3 on 10 Jun 11.2 on 26 Jul 2009 26 18.7
Horsley Park Equestrian Centre AWS 8.9 on 10 Jun 10.9 on 13 Jul 2011 24 18.0



Summary statistics for winter 2021
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
winter
2021
Diff
from
average
Highest for
winter
2021
Mean for
winter
2021
Diff
from
average
Lowest for
winter
2021
Total for
winter
2021
Average
for
winter
Rank of
winter
2021
Fraction of
winter
average
Badgerys Creek AWS 18.5 +0.3 27.7 22 Aug 4.3 -0.5 -1.3 30 Jul 109.2 119.7 average 91%
Bankstown Airport AWS 18.8 +0.7 27.6 22 Aug 6.2 +0.2 0.6 30 Jul 132.0 173.3 average 76%
Camden Airport AWS 18.1 0.0 27.3 22 Aug 3.6 -0.2 -2.1 22 Jul 102.2 145.1 average 70%
Campbelltown (Mount Annan) 18.5 +0.2 27.9 22 Aug 4.5 -0.3 -1.1 30 Jul 109.8 157.1 average 70%
Canterbury Racecourse AWS 18.4 +0.2 26.4 22 Aug 6.0 -0.4 1.2 30 Jul 185.4 227.0 average 82%
Cooranbong (Lake Macquarie AWS) 19.1 +0.1 26.6 1 Aug 5.1 -0.6 -1.8 30 Jul 136.8 206.6 low 66%
Gosford AWS 18.4   26.4 22 Aug 7.4   0.8 30 Jul 184.6
Holsworthy Aerodrome AWS 17.9   27.0 22 Aug 5.8   0.3 30 Jul 132.8
Holsworthy Defence AWS 17.5   26.5 22 Aug 6.1   0.7 10 Jun 140.8
Horsley Park Equestrian Centre AWS 18.2 +0.2 26.8 22 Aug 6.1 -0.4 -0.2 22 Jul 114.4 148.9 average 77%
Katoomba (Farnells Rd) 11.4 +1.1 18.3 23 Aug 3.5 +0.3 -1.0 10 Jun 162.0 278.1 average 58%
Mangrove Mountain AWS 17.3 +0.9 25.7 22 Aug 5.9 -0.7 -0.5 22 Jul 186.6 216.6 average 86%
Mount Boyce AWS 10.3 0.0 19.5 22 Aug 3.0 -0.1 -1.6 6 Jul 143.4 176.3 average 81%
Norah Head AWS 18.6 +0.5 26.8 1 Aug 10.3 -0.2 6.0 11 Jun 206.6 309.1 average 67%
Parramatta North (Masons Drive) 18.6 +0.5 26.7 22 Aug 7.5 +0.6 2.3 30 Jul 141.8 193.1 average 73%
Penrith Lakes AWS 19.0 +0.3 28.6 22 Aug 5.5 -0.6 -0.6 22 Jul 89.0 106.9 average 83%
Richmond RAAF 18.7 +0.2 27.5 22 Aug 4.3 -0.1 -2.7 30 Jul 105.2 115.6 average 91%
Sydney (Observatory Hill) 19.0   25.6 1 Aug 9.4   5.2 22 Jul 200.2
Sydney Airport AMO 18.9 +1.2 26.1 22 Aug 9.4 +1.3 4.6 11 Jun 217.0 269.1 average 81%
Sydney Harbour (Wedding Cake West) 17.8 +0.1 24.5 28 Jul 11.1 0.0 7.2 11 Jun
Sydney Olympic Park AWS (Archery Centre) 19.0   27.9 22 Aug 7.0   1.8 30 Jul 134.4 235.2 low 57%
Terrey Hills AWS 17.2 +0.3 24.5 22 Aug 8.1 -0.2 2.9 30 Jul 176.8 248.6 average 71%

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 10 am on Wednesday 1 September 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