From GNS:

 

Recent visits to the volcano have confirmed an increase in the output of volcanic gas from Mt Ruapehu’s Crater Lake. Moderate levels of volcanic tremor continue and the lake temperature measured by the outlet data logger is 45 ºC. The increase in gas output, the high lake temperature and continued seismicity suggest that Ruapehu is at a higher level of volcanic unrest. As a result, GNS scientists revise the Volcanic Alert Level to Level 2 (moderate to heightened unrest). The Aviation Colour Code is also changed, from Green to Yellow.

 

Of course it could die down and fall back to normal background activity, or it might really upset skiers this season.