Australian Capital Territory in 2020: wet with warm nights

The ACT had a wetter than average year in 2020, contrasting with the dry conditions of the previous three years. Minimum temperatures were generally well above average, while maximum temperatures were close to average despite a hot start to the year.

A wet year throughout the ACT

  • It was a wet year throughout the ACT, with annual rainfall 25% to 45% above average at most locations.
  • This follows three successive dry years in 2017, 2018 and 2019.
  • August and October were especially wet, with Canberra Airport receiving more than double its average monthly rainfall in both months.
  • Heavy rain fell on numerous occasions between late July and November, causing river rises and disruptions to low-level river crossings, although only once (on 8-9 August) did the Molonglo River reach minor flood warning thresholds.
  • March and April were also significantly wetter than average.
  • The only month in which rainfall at Canberra Airport was less than half the monthly average was January.

Warm nights, days near average

  • Minimum temperatures were well above average at low-elevation sites in the ACT, although near average at Mount Ginini.
  • Maximum temperatures were generally close to average.
  • January was a very warm month, although not as hot as January 2019, with maximum and minimum temperatures both ranking in the ten highest on record at Canberra Airport.
  • There were 9 days of 35 °C or above at Canberra Airport in 2020. This is above the long-term average of 5 but the fewest in a year since 2015. 7 of these days were in January.
  • Maximum temperatures were also well above average in July, which was the fourth-warmest on record at Canberra Airport.
  • Autumn days were cool, with all three months having maximum temperatures below average. Canberra Airport had its lowest autumn mean maximum temperature since 1984.
  • Maximum temperatures were also below average in December.
  • Nights were particularly warm in spring. Canberra Airport had its highest spring mean minimum temperatures on record, and its second-highest October mean minimum temperatures.
  • Minimum temperatures were also above average in most other months, except for March, May and June when they were close to average.
  • There were 42 nights with minimum temperatures at Canberra Airport below 0 °C , well below the average of 61. This was the lowest number of nights below freezing since 2009.
  • Some sites had their highest temperature on record.
  • Some sites had their warmest night (highest daily minimum temperature) on record.

Canberra Airport

  • Total rainfall for Canberra Airport was 790.0 mm, which is 129% of the long-term average of 612.3 mm and the highest since 2010.
  • The mean daily maximum temperature for Canberra Airport was 20.4 °C, which is 0.5 °C above the long-term average of 19.9 °C but was the lowest since 2012.
  • The warmest day was 44.0 °C on 4 January, and the coolest day was on 22 August when the temperature reached 7.5 °C, when snow fell in many suburbs and settled widely above 750 metres.
  • The mean daily minimum temperature for Canberra Airport was 7.6 °C, which is 1.1 °C above the long-term average of 6.5 °C.
  • The coldest morning was -4.9 °C on 5 June, and the warmest morning was on 2 February when the minimum temperature was 26.7 °C.

Other features of 2020

  • The Orroral Valley fire, which broke out on 27 January, burned 80% of the Namadgi National Park, as well as surrounding areas of the ACT and New South Wales. It was declared contained on 10 February following heavy rain.
  • Severe smoke pollution from fires in the ACT and southern New South Wales affected the ACT for much of January and February, with air quality in the hazardous range on many days.
  • The ACT had its hottest ever day on 4 January, when the temperature reached 44.0 °C at Canberra Airport. This is a record for any ACT site, surpassing the 42.8 °C at Acton on 11 January 1939.
  • Further extreme heat affected the ACT at the start of February. Canberra Airport had its hottest February day on record there on the 1st with 42.7 °C, whilst the minimum of 26.7 °C on the 2nd was a record there for any month. The ACT record high minimum is 27.2 °C at Acton on 14 January 1939.
  • Combined with the record set in December 2019, Canberra Airport had its hottest day on record for each of the three summer months.
  • One of the most severe hailstorms recorded in the ACT occurred on 20 January. Hail of 4 to 6 cm in diameter fell across a region extending from the southern half of Belconnen through Acton to the inner southern suburbs. Extensive damage was reported to buildings and motor vehicles, with insured losses of several hundred million dollars.
  • A major early-season cold outbreak, with snow in the Brindabellas, affected the ACT at the end of April. 9.7 °C at Canberra Airport on 30 April was the first maximum below 10 °C there in April since 1952.

Further information

Media
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Extremes in 2020
Hottest day 44.0 °C at Canberra Airport on 4 Jan
Warmest days on average 20.4 °C at Canberra Airport
20.4 °C at Tuggeranong (Isabella Plains) AWS
Coolest days on average 11.4 °C at Mount Ginini AWS
Coldest day -3.4 °C at Mount Ginini AWS on 22 Aug
Coldest night -7.2 °C at Mount Ginini AWS on 5 Aug
Coolest nights on average 3.5 °C at Mount Ginini AWS
Warmest nights on average 7.7 °C at Tuggeranong (Isabella Plains) AWS
Warmest night 26.7 °C at Canberra Airport on 2 Feb
26.7 °C at Tuggeranong (Isabella Plains) AWS on 2 Feb
Warmest on average overall 14.0 °C at Canberra Airport
14.0 °C at Tuggeranong (Isabella Plains) AWS
Coolest on average overall 7.5 °C at Mount Ginini AWS
Wettest overall 1539.0 mm at Mount Ginini AWS
Driest overall 790.0 mm at Canberra Airport
Wettest day 77.2 mm at Ginninderra (Charnwood (ACT)) on 10 Feb
Strongest wind gust 117 km/h at Canberra Airport on 20 Jan

Record highest temperature
New record
(°C)
Old
record
Years of
record
Annual
average
Tuggeranong (Isabella Plains) AWS 43.3 on 4 Jan 41.1 on 10 Feb 2017 25 20.9



Record highest daily minimum temperature
New record
(°C)
Old
record
Years of
record
Annual
average
Tuggeranong (Isabella Plains) AWS 26.7 on 2 Feb 23.1 on 20 Dec 2017 25 7.0



Summary statistics for 2020
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean
for
2020
Diff
from
average
Highest
for
2020
Mean
for
2020
Diff
from
average
Lowest
for
2020
Total
for
2020
Average
annual
total
Rank
of
2020
Fraction
of annual
average
Canberra Airport 20.4 +0.5 44.0 4 Jan 7.6 +1.1 -4.9 5 Jun 790.0 612.3 high 129%
Mount Ginini AWS 11.4 -0.5 33.2 4 Jan 3.5 -0.1 -7.2 5 Aug 1539.0 1051.2 high 146%
Tuggeranong (Isabella Plains) AWS 20.4 -0.5 43.3 4 Jan 7.7 +0.7 -4.7 6 Aug 902.4 620.5 high 145%
Note: Observations for “Canberra Airport” are taken from the current site (Bureau number 070351), which opened in late 2008.
Comparisons are made against data from the previous site Canberra Airport Comparison (070014), which ran from 1939 to 2010,
combined with the current site from March 2010 onwards.

Notes

The Annual climate summary, generally published on the second working day of the year, lists the main features of the weather in Australian Capital Territory 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 Australian Capital Territory “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 4 January 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