Scientists monitoring Mount Ruapehu plan to visit the volcano this week, to carry out further tests at the crater lake.
Earlier this week, GNS Science said the lake's temperature was about four degrees under its highest recorded level.
Increases in seismic activity and carbon dioxide emissions have also been recorded, along with changes in lake chemistry.
GNS Science says the temperature has now dropped by several degrees and is sitting at about 35 degrees celsius.
