While temperatures dropped and cumulus clouds gathered, rain refused to join the party.

The Ballarat region recorded just 18.8mm of rain in the past 31 days - 47.4mm below the monthly average.

It was the third consecutive month of below average rainfall and raised growing fears of a possible El Nino weather pattern.

Yet despite autumn's paltry precipitation, water storage levels remained significantly above 2004 levels.

The region received only 37.6mm in March, April and May.

A Central Highlands Water spokeswoman said despite poor rainfall figures, catchment levels remained good.

"For the first four months of the year rainfall in the catchment was 30 per cent below average."

Ballarat's water storage levels fell a drop below 40 per cent by the end of May.

Holding more than 25,000 megalitres, the level remained significantly higher than the same time last year when storage levels dived to 25 per cent.

But water users were urged to keep up their watersaving habits.

"It has been very dry and we would be encouraging customers to use water sparingly and abide by the stage two water restrictions currently in place in Ballarat and district," the spokeswoman said.

The lack of rain didn't equate to warm weather though, with average daily temperatures falling to 15.6C in May.

The mercury dipped below zero for the first time in 2005 with an overnight low of -1.5C on Monday, May 9.

And if you were hoping for a cloudburst, now may be the time to dig out the rain dance costume.

The Bureau of Meteorology is forecasting a dry winter with a 65 per cent chance of below average rainfall.

According to the bureau, indications from the Southern Oscillation Index and warming of the Pacific Ocean also point to an increased chance of an El Nino developing this year.