In what was a disappointing rainfall month, most of the region received only between half and three quarters of its normal totals for May. The latest 30-year average for May rainfall in Geelong is 41.5 mm, but this month we only received around 30 mm. Even the Otway towns from Beech Forest to Lavers Hill only recorded 75-80% of normal falls. The Moorabool catchment and the Golden Plains were even less fortunate with below half the average. In spite of this the overall water situation is still healthier than at the same time last year: Barwon Water reports that the capacity is at 70%.
Autumn’s rainfall overall was almost identical to the most recent 30-year average of 109 mm. This year’s autumn total for the Geelong urban area was 108 mm owing to well above average falls in April. In the last 30 years autumn rainfall has been declining but this year did not really continue that trend.
Probably the most significant feature of the temperature this month is that a new record was created when we had ten consecutive days over 20 degrees from the 13th to the 22nd. This ‘mild wave’ beat the previous record of nine days set in 1904, and it was caused by a very large ‘blocking’ high pressure system which parked over the NSW coast and diverted several rain-bearing fronts and low pressure systems southward towards Tasmania. There were only two other over-20 degree days.
With an average daily maximum of 19.0 degrees and minimum of 9.2 degrees, Geelong was around 1.5 degrees warmer than the May 30-year mean of 12.6 degrees. The warmest day reached 25.3 degrees on the 16th and the lowest maximum was 14.3 degrees on the 7th. The lowest minimum was 2.0 degrees on the 8th. It was Geelong’s third warmest May on record.
As far as the whole of autumn is concerned, this year’s 16.2 degree mean was 1.0 degree higher than the 30-year average of 15.2, but certainly not a record. Our warmest autumn occurred in 1988 with a mean of 16.6 degrees. It was Geelong’s sixth warmest autumn.
Once again it was a very unusual and settled month, with no severe storms, no strong wind days, no thunder days, only one frost and a ten-day run of mild days over 20 degrees.