Wireless Sensor Networks (WSN) with opportunistic links cannot guarantee end-to-end connectivity. This study proposes the OFZ-LEACH energy-efficient clustering protocol that forms Far-Zones based on nodal energy thresholds and uses Exponentially Weighted Moving Average (EWMA) to update nodal contact probabilities for cluster formation and gateway selection. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering. © 2012 Elsevier B.V., All rights reserved.