Wednesday 1 March 2006

SYDNEY MONTHLY CLIMATE SUMMARY - NSW REGIONAL OFFICE

3rd warmest summer on record for Sydney

Summer 2005-06 - Main points:

• 3rd warmest summer on record (warmest was in 1991)
• 6th consecutive summer with above average temperatures
• Many hot days. 19 days above 30°C  (average 9 days)
• Many warm nights. 47 nights above 20°C  (average 17 nights)
• Below average rainfall

February 2006 - Main Points:

• 7th warmest February on record
• Many warm nights. 18 nights above 20°C  (average 8 nights)
• Below average rainfall

Summer 2005-06

Temperatures:   Sydney residents experienced their 3rd warmest summer since records commenced in 1859 and the 6th consecutive summer with above average temperatures. The average summer temperature of 23.9°C (the average of daytime and night-time temperatures) was well above the historic average of 22.4 deg. Sydney's hottest summer was in 1991 with an average temperature of 24.6°C.   The average daytime maximum temperature (27.8°C) was also well above the historic average by nearly 2°C. It was equal 2nd highest on record and the same as 1998.

Sydney Observatory Hill (the official CBD site) recorded 19 hot days (temperature exceeding 30°C) during summer, more than double the historic average of 9 days.  However, the western suburbs sweltered through 49 hot days during summer (historic average 38 days). Many of these days, especially during January, were accompanied by high humidity, making conditions uncomfortable at times.  Warm summer nights were particularly common, the temperature not falling below 20°C on 47 nights at Observatory Hill, almost three times the historic average of 17 nights above 20°C. During one warm spell in January there were 11 consecutive nights above 20°C.

The highest temperature during summer was 44.2°C on New Years Day, the 2nd highest temperature ever recorded at Sydney Observatory Hill.  The coolest night was 15.2°C on 20 December.  Corresponding extremes across the Sydney metropolitan area ranged from 45.2°C at Sydney Airport on 1 January to a low of 8.5°C at Badgery's Creek on 20 December.

Rainfall:   Sydney's summer rainfall of 197.8mm was below the historic average of 298mm. The number of rain days (35) was average.  There were fewer thunderstorms than usual during summer, 7 storms being recorded at Observatory Hill against the historic average of 9 storms. The most severe was on 26 February when heavy rain caused local flooding in Sydney's north and west with 101mm recorded at Avalon and 94mm at Glenmore Park. Suburban rainfall totals for summer ranged from a high of 342mm at Avalon on Sydney's northern beaches to a low of 124mm at Sydney Airport.

February 2006

Temperatures:    Above average temperatures persisted during February with Sydney recording its 7th warmest on record.  The average February temperature of 24.1°C (the average of daytime and night-time temperatures) was 1.4°C above the historic average of 22.7°C.   Night-time temperatures were particularly mild with Sydney experiencing 18 nights when the temperature did not fall below 20°C, more than twice the historic average of 8 nights.

The highest temperature recorded at Sydney Observatory Hill during February was 32.8°C on the 18th while the lowest was a mild 16.8°C on the 8th.  Corresponding extremes across the Sydney metropolitan area ranged from 40°C at Richmond on the 2nd to 9.1°C at Camden on the 28th.

Rainfall:    The monthly rainfall total of 51.2mm was well below the historic February average of 117mm. Nearly all the rain came from 3 thunderstorms during the second half of the month.  There were 11 rain days, close to the historic average of 12 days.  Suburban rainfall totals for February ranged from 129mm at Avalon on Sydney's northern beaches to 28mm at Rose Bay and Sydney Airport.

A severe thunderstorm during the evening of the 26th caused flash flooding in many suburbs with 38.4mm at Observatory Hill, the wettest day this month.  However, much heavier falls were recorded in Sydney's northern and western suburbs, the highest being 101mm at Avalon in Sydney's north and 94mm at Glenmore Park in Sydney's far west.  Horsley Park recorded 49mm in 1 hour during the thunderstorm.

February rainfall totals over the Warragamba Dam catchment were light and scattered ranging from 30-40mm in the lower catchment to less then 20mm in the upper catchment.  Recent rainfall over Sydney's catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html

This statement has been prepared based on information available at noon on 1/3/06. Although every effort has been made to check them, it is possible that results may change as new information becomes available.

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.

¹Averages: Average temperatures are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation.

Further information: Contact Mike De Salis 9296 1542, email: reqnsw@bom.gov.au

A directory of Bureau services is available on poll fax: 1800 630 100

The latest rainfall and temperature maps are available here
Climate averages for New South Wales localities are available here
Daily Weather Observations for selected New South Wales localities are available here