The Rotorua District Council is urging locals to be on the lookout for smoke or fires around Sulphur Point and Ngapuna following a number of small sulphur fires in the past two weeks.
Council geothermal inspector Peter Brownbridge said sulphur fires were natural events which could occur as a result of sulphur growing and pushing its way to the surface, forming yellow mounds.
Leaves and twigs from nearby tea trees accumulate on the mounds when there is no rain to wash it away.
A combination of heat in the ground and the sun can ignite the dry material, which in turn ignites the sulphur.
Mr Brownbridge said in the past couple of weeks there had been four sulphur fires in the Sulphur Point area alone.