Sydney in summer 2014-15: Warm nights and thunderstorms

Rainfall was generally average to above average across the Sydney region during summer, with most of the rain falling during periods of thunderstorm activity. There were 17 days with thunder heard at Sydney Airport, well above average for summer and the most since summer 1985-6, including a record 7 consecutive days between 2 and 8 December. These contributed to locally heavy rain, with daily totals exceeding 50 mm on multiple occasions across the city. The heaviest rain fell between 27 and 29 January, with totals to 9 am on the 28th including 57 mm at Observatory Hill and 105.2 mm at Duffys Forest.

Minimum temperatures were well above average across the Sydney region, associated with above average rainfall and sea surface temperatures. At Observatory Hill the mean minimum temperature was 1.6 °C above average and the sixth-warmest on record. There were 52 nights that remained above 20 °C, more than double the historical average of 21 nights. This is the equal-second-greatest number of warm nights on record, behind 64 nights in summer 1990-91. This included 17 consecutive warm nights between 9 and 25 February, the second-longest warm spell on record for Sydney behind 18 days in summer 2009-10.

In comparison, maximum temperatures were generally close to average in western Sydney, with very cool days at the end of January, but 1.2 °C above average at Observatory Hill. Only seven days reached at least 30 °C during the summer, below the historical average of 9 days. However, only 21 days were below 25 °C, half the average of 41 cool days and the equal-fourth-fewest on record.

  • Persistent thunderstorms cause locally heavy rain
  • Sixth-warmest summer on record for mean minimum temperatures
  • Mild summer with few cool days
  • Second-longest spell of warm nights on record

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Extremes in summer 2014-15
Hottest day 37.7 °C at Richmond RAAF on 3 Dec 2014
Warmest days on average 29.4 °C at Penrith Lakes AWS
Coolest days on average 25.6 °C at Terrey Hills AWS
Coldest day 18.5 °C at Springwood (Valley Heights) on 19 Jan 2015
18.5 °C at Terrey Hills AWS on 28 Jan 2015
Coldest night 10.2 °C at Camden Airport AWS on 30 Jan 2015
Coolest nights on average 16.9 °C at Campbelltown (Mount Annan)
Warmest nights on average 20.1 °C at Sydney Airport AMO
Warmest night 23.4 °C at Sydney Airport AMO on 23 Jan 2015
Warmest on average overall 24.0 °C at Penrith Lakes AWS
Coolest on average overall 21.8 °C at Terrey Hills AWS
Wettest overall 530.6 mm at Turramurra (Kissing Point Road)
Driest overall 276.0 mm at Willmot (Resolution Ave)
Wettest day 105.2 mm at Duffys Forest (Namba Rd) on 28 Jan 2015
Strongest wind gust 89 km/h at Camden Airport AWS on 7 Dec 2014
89 km/h at Richmond RAAF on 22 Dec 2014

Summary statistics for summer 2014-15
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2014-15
Diff
from
average
Highest for
summer
2014-15
Mean for
summer
2014-15
Diff
from
average
Lowest for
summer
2014-15
Total for
summer
2014-15
Average
for
summer
Rank of
summer
2014-15
Fraction of
summer
average
Badgerys Creek AWS 28.6 -0.2 36.5 3 Dec 2014 17.6 +1.2 11.9 30 Jan 2015 307.0 248.8 high 123%
Bankstown Airport AWS 28.5 +0.7 37.0 25 Jan 2015 18.5 +0.9 11.5 30 Jan 2015 338.6 265.3 high 128%
Camden Airport AWS 28.7 -0.1 37.3 8 Feb 2015 17.0 +0.8 10.2 30 Jan 2015 330.8 239.4 high 138%
Campbelltown (Mount Annan) 28.4   36.2 3 Dec 2014 16.9   10.7 30 Jan 2015 264.6
Canterbury Racecourse AWS 26.9 -0.2 35.9 25 Jan 2015 18.1 +0.3 10.3 30 Jan 2015
Holsworthy Aerodrome AWS 28.0   37.3 25 Jan 2015 17.9   10.6 30 Jan 2015 242.2
Horsley Park Equestrian Centre AWS 28.1 -0.7 35.8 9 Jan 2015 17.6 +0.4 10.6 30 Jan 2015 349.6 247.9 high 141%
Parramatta North (Masons Drive) 27.8 -0.1 36.5 25 Jan 2015 17.9 +0.8 12.3 30 Jan 2015 445.0 303.5 high 147%
Penrith Lakes AWS 29.4 -0.4 37.3 8 Feb 2015 18.6 +0.7 13.7 30 Jan 2015 351.8 277.9 high 127%
Prospect Reservoir 28.5 +0.6 36.0 3 Dec 2014 18.0 +0.7 12.1 30 Jan 2015 434.3 265.7 high 163%
Richmond RAAF 29.1 -0.1 37.7 3 Dec 2014 18.1 +1.0 11.9 30 Jan 2015 467.6 283.7 v high 165%
Sydney (Observatory Hill) 26.8 +1.2 35.7 17 Jan 2015 20.0 +1.6 14.6 29 Jan 2015 341.8 296.7 average 115%
Sydney Airport AMO 27.6 +1.4 36.6 25 Jan 2015 20.1 +1.6 14.3 30 Jan 2015 283.6 279.9 average 101%
Terrey Hills AWS 25.6 -0.2 33.4 17 Jan 2015 17.9 +0.4 13.0 14 Dec 2014 403.8 321.7 high 126%

Notes

A Seasonal Climate Summary is prepared to list the main features of the weather in Sydney using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

A Climate Summary is generally published on the first working day of each month.

This statement has been prepared based on information available at 8 am on Monday 2 March 2015. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

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.

The ACORN-SAT dataset is used for temperature area averages.

Further information

Media
(03) 9669 4057
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