May 2017 had 3 distinct phases: a colder than normal first fortnight, a warmer than normal 3rd week and a colder final week. All these variations averaged out into a fractionally cooler month overall. Minimums averaged 8.0 C (mean 8.3 C) and maximums averaged 17.0 C (mean 17.1 C), giving a figure 0.2 C below the May 30-year mean temperature.
The warmest day was the 21st (20.8 degrees C) and the coldest day was the 16th (13.0 C). Overnight minimum temperatures varied from 3.5 C on the 12th to 13.7 C on the 23rd.
Photo above: Foggy day on Corio Bay 17-5-2017, courtesy Harry De Wit.
Very poor rainfall in May (27.8 mm in urban Geelong) was experienced over most of the region. Only between 40% and 60% of the normal rain was recorded from the Otways to the Bellarine Peninsula. Rain fell on 16 days and the heaviest recorded at Breakwater was 12.6 mm on the 28th.
Several massive forecast failures occurred during the month. On the 19th very heavy rainfalls were predicted for Geelong but only 0.2 mm eventuated, and several days had maximum temperatures well below those predicted. Basically the causes can be put down to the very difficult task of forecasting in a very changeable autumn.
Otherwise the month was settled. There were no strong wind gusts, no storms, no thunder days but several foggy mornings.
Autumn overall was very wet thanks to above average March and April; almost all places recorded well over double the seasonal rainfall average. However, owing to a warm March and April, autumn temperatures were slightly above average.