In late 2025, volcanologists noted that the temperature of Te Wai ā-moe had increased to around 17 °C.
Based on previous temperature patterns, we anticipated that it would continue rising. Instead, the lake temperature has fluctuated between approximately 14 and 19 °C. While this represents some variation, it is relatively minor and falls within the range observed over the past 16 years. Recent data suggests that the inflow of hotter fluids has decreased over the last few months. Similar patterns were recorded in 2012–13, 2014, 2019, and 2022.
Although the current inflow of hot fluid beneath the lake is relatively low, sulfur dioxide (SO₂) emissions remain at typical levels, indicating that the hydrothermal system is still open. Volcanic tremor activity continues to be weak. Taking all monitoring data into account, we assess the present activity as low-level and consistent with minor volcanic unrest. Accordingly, the Volcanic Alert Level remains at 1, and the Aviation Colour Code stays at Green.
The Volcanic Alert Level indicates the current state of volcanic unrest. It is not intended to predict future volcanic activity.