Koala carers are asking those living near colonies to help the animals find a drink.
President of Friends of the Koala, Lorraine Vass, says the spate of hot days and dry conditions have affected moisture levels in the eucalypt leaves they eat.
Ms Vass says many people wrongly assume koalas get all they need from the leaves.
But she says koalas often climb down their trees in the morning, so leaving a bowl of water at the bottom is a good idea.
"Koalas do get thirsty [and] when we've had sustained dry weather like the present time and the temperatures are really climbing, the trees around our place are looking awfully thin and sparse and the leaves that are left are really dry," she said.
"So, we just ask people to put out bowls of water at the base of the trees that they know koalas use."
© ABC 2013
08:27 EST Snow has fallen in parts of Victoria that rarely see snow, as a cold snap grips parts of the state.