ACT in Autumn 2010
Wettest Autumn for twenty years
* Wettest Autumn since 1990
* 8 days with rain above 10mm, seventh highest on record
* Above average maximum and minimum temperatures
Rainfall
Rainfall varied significantly in Canberra throughout autumn, with very
high totals in March and May offset by well below average rainfall during
April. The total rainfall at Canberra Airport during the season was
186.8mm, which is the highest Autumn rainfall since 1990 (226mm) and the
19th wettest on record. This is the first Autumn since 2000 to exceed the
average May rainfall of 141.2mm
This rain fell over 24 days, close to the Autumn average of 22. Of these,
eight days exceeded 10mm, double the average of 4.3 such days. This is the
seventh highest amount of high rain days in Autumn on record, and the
highest since 8 such days were recorded in Autumn 1990. Three days also
recorded rainfall above 20mm, associated with the passage of troughs on
March 8 and 31, and an East Coast Low on May 30.
The wettest location in the ACT during Autumn was 259.4mm at Mt Ginini
AWS, followed by 239.4mm at Tidbinbilla in the suburbs. The highest
rainfall recorded on any single day was associated with a low pressure
trough on the 8th of March, which brought 35mm at Canberra Airport,
reaching 78mm at Mt Ginini and 68mm at Tidbinbilla on the same day.
Some sites had their highest total autumn rainfall for at least 20 years.
Temperature
The mean temperature at Canberra Airport during May was 14.1°C, which was
0.7°C above the historical average of 13.4°C. This was associated with both
above average maximum and minimum temperatures through the season, with
particularly warm maximum temperatures during April and May.
Maximum temperatures at Canberra Airport averaged 20.8°C during Autumn,
0.8°C above the historical average of 20°C. This was associated with well
above average maximums in April and May, while temperatures were just 0.1°C
above average during March. However, this is the coolest autumn for maximum
temperatures since 2003 (20.4°C). Temperatures were warmest at Tuggeranong,
with 20.9°C, while the hottest day recorded during the season was 29.3°C at
Tuggeranong on March 26. These warm conditions were associated with
generally northerly winds and the clear and sunny conditions throughout the
month associated with the passage of high pressure systems, despite the
cooling effects of rain systems in March and late May.
Minimum temperatures averaged 7.4°C at canberra Airport during Autumn,
0.6°C above the historical average of 6.8°C. This was associated with well
above average overnight temperatures in March and April, although nights in
May were 0.1°C below average. Overnight minimums were warmer at
Tidbinbilla, averaging 7.6°C, with the lowest temperature recorded anywhere
in Canberra -4.8°C at Mt Ginini AWS on the 12th of May. The lowest in the
Canberra metropolitan area was -3.7°C at Canberra Airport on 13 May.
Wind
Winds were predominantly northerly to westerly during autumn, forming 64%
of 3pm windflow, significantly above the Autumn average of approximately
50% from this direction, contributing to the warm conditions. No strong
wind days were reported at Canberra Airport, with the maximum wind gust
just 61km/h on April 11. Higher winds were experienced at Mt Ginini
(elevation 1760m), which recorded the maximum wind gust anywhere in
Canberra of 87 km/h on May 30, associated with an East Coast Low.
Other phenomena
Canberra Airport averaged 7.6 hours of sunshine during Autumn, which is
above the historical average of 7.1 hours per day. Sunshine was highest in
April, which recorded 8.2 hours per day. Three thunderstorms were reported
during the season, with no significant dust storms.
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