30 April 1975
The World Meteorological Organization (WMO), which was created to facilitate international cooperation in the establishment of meteorological and related services and observations, suspended South Africa from the organisation until it renounced its racial discrimination policy. The decision to suspend SA was taken at its seventh Congress held in Geneva, Switzerland. South Africa regained its membership on 9 June 1994. In its three consecutive congresses in 1995, 1999 and 2003 South Africa was elected on to the Executive Council.
Sources:
http://www.dfa.gov.za/foreign/Multilateral/inter/wmo.htm Kalley, J.A.; Schoeman, E. & Andor, L.E. (eds)(1999). Southern African Political History: a chronology of key political events from independence to mid-1997, Westport: Greenwood.