Annual updates of this feature will be available from www.geelongweatherservices.com.au every January.
PAGE 55 MONTHLY TRENDS LINE 3 should read:
“4.25 shows that the most current 30-year average is now 28.1 mm. This places”
PAGE 57 LINE 3 should read:
“another with an increase in maximums matching the decrease in minimums.”
PAGE 80 MONTHLY TRENDS LINE 3 should read:
“point, 38 mm in 1902, up to 54 mm in 1965, down to 40 mm in 1995 and up again to”
Mean Annual Temperatures
The warmest year was in 2014, which had a mean temperature of 15.55°. A warming trend of 0.35° is noticeable in the 30-year averages between 1960 and the early 1990’s, but there has been a slight cooling since then of about 0.1°, then a recent warming. In Figures 2.2 and 5.9 it can be seen that Geelong’s 30-year mean temperature in 1932 was 14.5°, while in 2014 it was almost exactly the same.
Hottest Day (JANUARY)
This occurred on January 17th, 2014, when the temperature peaked at 45.4°. Maximums of 40° and above have occurred 66 times in January since 1903, an average of about 0.5 times per year. In January 1908 and again in 2014 there were five and four consecutive days over 40° respectively before cool changes finally relieved the heat waves. See page 38.
Hottest Day (APRIL)
April’s hottest day was 1-4-2014, when the temperature reached 35.7°. This passed the record 34.9° set in 1922. In April 2014 there was no heat wave, but in 1922 the previous two days had also reached over 30° and a 3-day heat wave in this month is extremely rare, although a day of 30° or more is to be expected on average every couple of years.
Longest Heat Wave (MAY)
Since the term ‘heat wave’ does not strictly apply, the best we can do is to find the longest uninterrupted period in May where temperatures have exceeded 20°. This unprecedented event of ten days in 2014, averaging 22.8°, was caused by a massive blocking high which dominated southeastern Australia on the ten consecutive days between the 13th and the 22nd, as seen in Figure 4.40 below.
DATE MAX °
Fig. 4.40: The longest ‘heat wave’ in May was in 2014 with 10 consecutive days over 20°. Source: BoM data.
Until 2014 the longest consecutive number of days (9) above 20° in May occurred in 1904. Several other Mays have recorded six and seven such days, and were usually caused by a blocking high pressure system (see page 13).
Warmest Night (JULY)
Normally Geelong would be expected to experience an overnight minimum of more than 10° in July only occasionally, so the record high minimum of 13.8° on 31-7-2014 is interesting. Actually a total of four nights over 10° occurred in July, 2014, and the end result is that that month holds the equal highest average minimum record for July with 1998, namely 7.2° or two degrees above the long-term average.
In 2011 and 2014 occurred the warmest springs each with a mean temperature of 15.3°. 2014 had the highest spring mean maximum (21.1°) and 1949 had the warmest nights (average minimum 10.1°), but 2011 and 2014 hold the record because of their overall means.