30/09/2010: After their coldest winter in 13 years Sydney residents have just experienced their coldest September in five years, according to weatherzone.com.au.

The city had an average maximum temperature of 21 degrees, making it the coldest September in terms of daytime temperatures in three years. This is despite being warmer than the long-term norm of 20. The most notable feature was a lack of warm days. It took until the 27th to warm to 27 degrees, the longest it's taken in 17 years. There was a 23-day period that stayed colder than 25 degrees, the longest in September in 10 years.

The nights were not particularly cold overall, averaging a minimum of 12.3 degrees, one above the long-term average. This made it the coldest in terms of overnight minimums in two years. There were only six nights that cooled below 10 degrees, typically there are are 11 nights.

When both daytime and overnight temperatures were combined, Sydney’s average temperature came in at just under 17 degrees. This made it the coldest September in five years, despite being one degree above the the long-term norm.

"September was an unusual month in terms of the lack of warm days across much of southeastern Australia. A high pressure system over the Great Australian Bight acted as a blocking mechanism, keeping noticeably cool southerly winds blowing over South Australia, Victoria and New South Wales," Weatherzone meteorologist Brett Dutschke said.

The cold was a feature across southern and central New South Wales with several centres including Hay and Forbes having their coldest September in at least 15 years in terms of daytime temperatures.

As far as rainfall goes, Sydney failed to receive the long-term monthly average of 69mm, despite having the normal number of rain days, 10. The city only gained 42mm, the lowest for September since 2007.

"The bulk of Sydney’s rain fell on the 13th in a spell of onshore winds after a mild day. During this spell much of inland NSW had rain and thunderstorms which brought a month's rain in a day to some parts and led to flooding," Dutschke said.

Some areas ended up with more than double the monthly average with help from feeds of tropical moisture. Many had their wettest September in five to 10 years, including Moree, Mudgee, Orange, West Wyalong and Albury.

"Looking ahead, significant warming will occur in the coming weeks as heat builds over the interior. All we will need as a day or two of westerly winds and we could exceed 30 degrees," Dutschke said.

"With La Nina likely to peak in the next few months, we are expecting rainfall to increase, trending to near or above average into summer. During this period daytime temperatures should be near or below average. Overnight temperatures are likely to be close to normal."

Media Inquiries:

Brett Dutschke
media@weatherzone.com.au
02 9965 9269

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