Its recent lease agreement for the island expired in July, the department said in a statement.
“[We] use the island to collect research data and make weather observations that are crucial for South Africa and the world,” the department said.
“The quality of South African weather forecasts relies heavily on the availability of data inputs from the Gough Island region.”
Meteorological data also helped with global forecasting models.
“The current data collection from Gough Island exceeds 55 years,” it said.
In terms of the agreement, South Africa will transport a limited number of UK citizens and cargo on the SA Agulhas II, at a concessionary rate, between Cape Town and Tristan da Cunha.
The department’s director general Nosipho Ngcaba was due to sign the agreement on Tuesday.