'Unheard of': First six months of year some of the driest since 1900

Senior climatologist Jonathan Pollock said the south-west had seen well below average rainfall in June than in previous years.

"Warrnambool had less than half its average rainfall," Mr Pollock said.

"Warrnambool Airport recorded 34.2 millimeters and it has a long term average of 81.8 millimeters."

Other areas in the south-west also recorded lower than average rainfall.

Hamilton recorded 28.2 millimeters of rain for June and Portland only recorded 22.5 millimeters.

Mr Pollock said the weather had the makings of a green drought for the region.

Owner of Bellman's Water Gary Kelly said June was typically a quieter month for him, but this year he had seen unprecedented demand for water delivery.

"Normally this time of year things would have slowed right down with the rain, but it's just continued on," Mr Kelly said.

"This year is certainly one out of the bag.

"It's we just haven't had the rainfall."

Mr Kelly said he and his sons had been "flat out" since January.

Instead of running two trucks, they have been running four to keep up with demand.

He said for a lot of his consumers buying water in June was "unheard of."

"Normally we would have plenty of rain by now," Mr Kelly said.

"People wouldn't be buying water because they've run out, it's more probably because they've left the tap on, than just run out because there's been no rain."

Mr Kelly said even with some rain that had arrived it "wasn't enough to fill a tank" and he expected to stay busy until more water eventually fell