The temperature of Mount Ruapehu's crater lake has risen to 22C and earthquakes are rattling the volcano - but an expert says it's no cause for concern.
Volcanologist Brad Scott says every year the lake goes through heating and cooling cycles which are tracked by GeoNet - in late September the lake reached its coldest temperature of 12C and is now beginning to warm again.
Scott says the recent warming is normal for this time of year.
"None of these observations are unusual for Mt Ruapehu," he said on Tuesday.
"All observations over the past months indicate that the volcano remains in a general state of minor unrest."
As well as the increase in temperature, small earthquakes continuously rock the mountain - but this is normal for an active volcano.
The alert level for the volcano is at 1, but Scott warns it can erupt with little or no warning.
"The volcanic alert level reflects the current level of volcanic activity and is not a forecast of future activity."
GeoNet will continue to closely monitor the volcanic activity at Mt Ruapehu with a network of seismic sensors and flights to collect and analyse the volcanic gases.
The volcano last erupted in May 2007, causing two lahars and prompting the evacuation of some ski lodges on the slopes.
