GEELONG has experienced its hottest and one of the driest Octobers since records began for temperatures in 1903 and rain in 1871.
The combination left the region’s storages below 60 per cent of capacity after the end of the month, despite a final-day deluge.
The previously hottest October was in 1940 when the mean temperature was 15.9C. This year it was 17.1C, compared to the latest 30-year average of 13.7C.
The most likely culprit for the 2015 record was not man-made global warming but a combination of a very strong El Nino and a positive Indian Ocean Dipole (IOD) together with the ever-present rain-shadow effect from the Otway Ranges and the Great Divide.
When the first two features combine they provide warm dry air masses from the northeast and northwest, which have full sway over southern Victoria to produce the optimum conditions for record-breaking heat and aridity.
Very low rainfall was experienced right across western Victoria, including the Geelong region. Despite a thunderstorm dumping around 10mm-plus up to 9am on the last day of the month, the totals remained generally below 30 to 50 per cent of normal October falls.
The urban average was only 17mm compared to the latest 30-year October average of 53.8mm.
The region’s storages were 58.4 per cent this week.
Numerous temperature records were broken in October.
The highest daily maximum average was a record 24.1C compared to the 30-year average of 19.1C. The previous highest 22.9C was in 1914.
The October mean temperature was the highest since 1903 when records began, with 17.1C recorded compared to the previous highest of 15.9C in 1940.
The region recorded its warmest first week in October, with three days over 30C.
The other records were: six days over 30C, equal with 1977; 21 days over 20C compared to the average 10.5 days; and 13 nights over 10C, equal with 1963.
The maximum temperature for the month was 35.5C on 5 October. The lowest overnight was 2.9C on the first day of the month.
The highest overnight minimum was 15.9C on 21 October and the coldest day was 15.5C on the 22nd.
Three strong wind days were recorded for the month, with a maximum gust of 78km/h at Breakwater’s weather station on 7 October.
One thunderstorm was recorded on 31 October but the month was free of severe storms.
