Monday, 2 June 2008 - Seasonal Climate Summary for Canberra_AWS - Product code IDCKGC2xx0

Canberra in autumn 2008
The drying trend of autumn continues

Summary

  • 11th driest autumn on record at Canberra Airport
  • 8th consecutive autumn with below average rainfall
  • 11th warmest autumn on record for average maximum temperatures
  • 4th sunniest autumn on record at Canberra Airport

Rainfall

Persistent high pressure systems that extended across the ACT during autumn resulted in dry, settled weather throughout the season. The total autumn rainfall of 60.2 mm at Canberra Airport was well below the historical autumn average1 of 151.4 mm. This is the 11th driest autumn on record for Canberra Airport (current driest is 13.4 mm set in autumn 2004) and the driest autumn since 2006 (55.0 mm). It also marks the 8th consecutive autumn with below average rainfall, and a continuation of the drying trend that has affected the south-east Australian region since the mid 1990s.

See a map of total rainfall. See a map of rainfall deciles.

Temperature

Warm days and cool nights prevailed during autumn. Persistent high pressure systems over the ACT during the season resulted in clear skies, light winds and dry conditions.

The average maximum temperature for autumn for Canberra Airport was 20.9°C, which is 1.0°C above the historical average1 of 19.9°C. This is the equal 11th warmest autumn on record for average maximum temperatures, and the 12th consecutive autumn with above average maximum temperatures.

The average minimum temperature for autumn for Canberra Airport was 6.2°C, which is 0.8°C below the historical average of 7.0°C. This is the coolest autumn since 2001 for average minimum temperatures at Canberra Airport.

The large variation between day-time and night-time temperatures in autumn resulted in a significant diurnal temperature range. The ACT recorded an average diurnal temperature range (difference between the mean minimum and mean maximum temperature) of 14.7°C, which is 1.8°C above the historical average of 12.9°C.

Some sites had their coldest autumn day (lowest maximum temperature) on record.

See a map of mean maximum temperatures. See a map of maximum temperature anomalies.

Some sites had their lowest autumn mean daily minimum temperature on record.

See a map of mean minimum temperatures. See a map of minimum temperature anomalies.

Wind

At Canberra Airport, the prevailing direction in autumn during the mornings (9am) was SE for about 37% of the time. During the afternoons (3pm) the prevailing direction was NW for 35% of the time.

Other phenomena

There were 3 thunderstorms (average 4) and 2 hail days (average nil) reported at Canberra Airport during autumn. Sunshine hours for autumn averaged 8.0 hours per day (average is 7.1 hours per day), which is the 4th sunniest autumn on record at Canberra Airport (records since 1978).  There were 19 frosts (average 19), and 16 fogs (average 16).

Further information

NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au

Extremes

Hottest day
Highest temperature
24.1°C at Canberra Airport on 12 Apr
24.1°C at Tuggeranong (Isabella Plains) AWS on 12 Apr
Warmest days on average
Highest mean daily maximum temperature
20.9°C at Canberra Airport
20.9°C at Tuggeranong (Isabella Plains) AWS
Coolest days on average
Lowest mean daily maximum temperature
11.5°C at Mount Ginini AWS
Coldest day
Lowest daily maximum temperature
−2.0°C at Mount Ginini AWS on 28 Apr
Coldest night
Lowest temperature
−5.0°C at Mount Ginini AWS on 29 Apr
Coolest nights on average
Lowest mean daily minimum temperature
3.5°C at Mount Ginini AWS
Warmest nights on average
Highest mean daily minimum temperature
6.2°C at Canberra Airport
Warmest night
Highest daily minimum temperature
10.0°C at Tidbinbilla Nature Reserve on 14 May
Wettest overall
Highest total rainfall
146.0 mm at Bendora Dam
Wettest day
Highest daily rainfall
75.0 mm at Bendora Dam on 3 Apr
Highest wind gust
83 km/h at Canberra Airport on 2 Apr

Records

Record lowest total autumn rainfall
Total rainfall
for autumn 2008 (mm)
Previous lowest
for autumn
Years of
record
Normal for
autumn
Ginninderra CSIRO 30.6 41.2 in 1965 42 154.1
Stromlo Forest 28.2 31.5 in 2006 34 153.5



Summaries

This table is very wide and may not fit if printed.

Summary statistics for autumn 2008
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2008
Diff
from
normal
Highest for
autumn
2008
Mean for
autumn
2008
Diff
from
normal
Lowest for
autumn
2008
Total for
autumn
2008
Normal
for
autumn
Rank of
autumn
2008
Fraction of
autumn
normal
Sthn Tablelands Gburn-Monaro (district 70)
Canberra Airport 20.9 +0.9 35.2 15 Mar 6.2 −0.6 −2.7 19 May 60.0 142.6 low 42%
Mount Ginini AWS* 11.5   25.3 15 Mar 3.5   −5.0 29 Apr 131.4
Tuggeranong 20.9 −0.3 35.8 15 Mar 5.2 −1.8 −3.5 19 May 58.8 80.4 normal 73%

* new station, historic averages not available


Notes

This statement has been prepared based on information available at 11 am on Monday 2 June 2008. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

1Averages:  historic average temperatures for Canberra Airport are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation. The historic average temperatures for Tuggeranong AWS are based on all available records 1996−2007. Rainfall averages at Canberra Airport are based on all years of record 1939−2007.

A note about deciles: Deciles are used to give an element (in this case rainfall or temperature) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest) then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc up to the highest annual totals (highest 10 per cent) being in decile range 10.

Normals are long-term averages 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 20 years of record for temperature and less than 30 years of record for rainfall, as they cannot then be calculated reliably.

Further information

NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au