Temperature is a physical property subject to a characteristic increase if the volcano is re-activated.

Therefore, monitoring of temperature variations constitutes a main, obligatory component of an integrated monitoring network.

Thermal monitoring on Nisyros is achieved through the continuous recording of the temperatures in Stefanos and Polyvotis Minor fumaroles, as well as the hot springs in Avlaki, Loutra and Yalos Tavla (Mandraki).

Temperatures of hot springs in Katsouni, Thermiani of Paloi, Emporeio cave, Pyria and other sites are subject to periodic monitoring (3-4 times a year).