The crater lake may be bubbling and heating up but there's no immediate worry of Mount Ruapehu erupting.

The lake temperature is currently at 44 Celsius which is on the higher end of its fluctuations.

GNS volcanologist Brad Scott said there are always safety concerns surrounding active volcanoes, but right now, there are no more worries than usual.

"Things that might make us a little bit more concerned could be seismic activity, could be ground defamation, could be heating or cooling rates in the lake."

He said the water in the lake goes through temperature cycles.

"About every sort of nine to 15 months it just cycles between that 15 and 44 and that's just what Mt Ruapehu does."

Mount Ruapehu last erupted in September 2007.