Monday, 2 February 2009 - Monthly Climate Summary for ACT Monthly Summary - Product code IDCKGC15R0

A hot and sunny January for the ACT

Summary

  • Sunniest month on record
  • Above average number of hot days in Canberra
  • 9th consecutive above average minimum and maximum temperatures for Canberra
  • Average to below average rainfall

An archive of previous monthly summaries for ACT Monthly Summary is also available, as are summaries for other states and many other climate summaries and diagnostics.

Rainfall

Canberra Airport recorded a total rainfall of 51.6 mm, which is just below the January average1 of 59.2 mm. The rain fell over 7 days in January, with most due to thunderstorm activity on the 20th, 22nd and 23rd of the month. Smaller totals were recorded for the 24 hours to 9am on the 12th, 13th, 23rd and 25th.

Most of the ACT recorded January rainfall totals of between 35 mm and 65 mm, which were close to or below average for the month. Mt Ginini recorded the Territory's highest falls of 79.4 mm, and the Botanic Gardens recorded the lowest falls of 36.2 mm.

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

Temperature

It was a very warm month in the ACT in January, with maximum temperatures being very much above average throughout the region (highest 10% of records). At Canberra Airport, the mean maximum temperature was 31.0°C, which is 3.1°C above the historical average of 27.9°C, and the equal 7th warmest on record. Of particular note, the last three days of the month all recorded temperatures greater than or equal to 37.0°C, which hasn't occurred since 1979 (when 5 consecutive days of maximum temperatures greater than or equal to 37°C were recorded). For the month of January 2009, there were 17 days that were greater than or equal to 30°C, compared to the average of 11 days, and 6 days that were greater than or equal to 35°C, compared to the average of 3 days. It is the 9th consecutive January with above average maximum temperatures. Much of this heat was as a result of persistent blocking high pressure systems in the Tasman Sea, which directed hot northwesterly winds over the region. There were very few cold fronts that penetrated the ACT to cool conditions down.

Overnight temperatures were slightly above average for the ACT, with most of the region recording minimum temperatures of close to or slightly above average. At Canberra Airport, minimum temperatures ranged from a low of 7.9°C on the 17th, to a high of 19.9°C on the 22nd. The mean minimum temperature was 14.0°C, which is 0.9°C above the historical average of 13.1°C. This is also the 9th consecutive January with above average minimum temperatures at the Airport.

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

Wind

There was a large increase in the frequency of winds coming for the NW quadrant this month (from west through to north). At 9am, 52% of observations from Canberra Airport were from this quadrant, which is more than double the frequency expected (average of 25%). In the afternoon at 3pm, 71% of the winds blew from the NW quadrant, compared to the expected 59% of winds. As described in the temperature section above, it is these winds that contributed to the warmer overall temperatures for the ACT this month.

It was a little more windy than usual in Canberra this month. At the Airport, the average strength of the wind at 9am was 10.2 km/hr (average of 7.4 km/hr), with speeds increasing to an average of 19.2 km/hr at 3pm, (average of 16.8 km/hr). The highest daily wind gust was 106 km/hr, recorded on the 20th, as a result of thunderstorm activity. There were 3 days where strong winds were recorded (average is 2 days) and no days of gale force winds (average 0 days).

Other phenomena

Canberra Airport experienced it's sunniest month on record, with an average of 11.8 hours of bright sunshine a day (previous record 11.4 hours in December 2005). This is 1.9 hours more than the January average of 9.9 hours a day. The total cloud amount was therefore below average, with an average of around 1/4 of the sky obscured by cloud each day, compared to the usual of about 1/2 of the sky obscured by cloud each day.

There were seven days with thunderstorm activity in the ACT (7th, 11th, and 20th to 24th), with hail being reported on the 20th. Reports on this day included 2cm hail at Yarralumla and 1−1.5 cm hail at Oxley. Hail was also reported at Canberra Airport (no size reported).

Further information

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

Extremes

Hottest day
Highest temperature
38.2°C at Canberra Airport on the 31st
38.2°C at Tuggeranong AWS on the 31st
Warmest days on average
Highest mean daily maximum temperature
31.3°C at Tuggeranong AWS
Coolest days on average
Lowest mean daily maximum temperature
22.0°C at Mount Ginini AWS
31.0°C at Canberra Airport
Coldest day
Lowest daily maximum temperature
14.0°C at Mount Ginini AWS on the 9th
Coldest night
Lowest temperature
1.0°C at Mount Ginini AWS on the 2nd
Coolest nights on average
Lowest mean daily minimum temperature
9.9°C at Mount Ginini AWS
14.0°C at Canberra Airport
Warmest nights on average
Highest mean daily minimum temperature
14.1°C at Tuggeranong (Isabella Plains) AWS
Warmest night
Highest daily minimum temperature
20.5°C at Tuggeranong (Isabella Plains) AWS on the 22nd
Wettest overall
Highest total rainfall
79.4 mm at Mount Ginini AWS
63.8 mm at Nicholls (Gungahlin Lakes)
Wettest day
Highest daily rainfall
33.0 mm at Mount Ginini AWS on the 23rd
Highest wind gust
106 km/h at Canberra Airport on the 20th

Summaries

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

Summary statistics for January 2009
Maximum temperatures
for January
(°C)
Minimum temperatures
for January
(°C)
Rainfall
for January
(millimetres)
Mean for
January
2009
Diff
from
average
Highest for
January
2009
Mean for
January
2009
Diff
from
average
Lowest for
January
2009
Total for
January
2009
Average
for
January
Rank of
January
2009
Fraction of
January
average
Canberra Airport 31.0 +3.1 38.2 31st 14.0 +0.9 7.9 17th 51.6 59.2 average 87%
Mount Ginini AWS 22.0   29.0 31st 9.9   1.0 2nd 79.4
Tuggeranong 31.3 +2.1 38.2 31st 14.1 0.0 9.0 10th 59.0 47.1 high 125%

Notes

This statement has been prepared based on information available at 10 am on Monday 2 February 2009. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

1 Averages 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.

Further information

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