Low Rate Wireless Personal Network (LR-WPAN) is basically designed for an environmental monitoring application in Wireless Sensor Networks (WSNs). Improvement of the LR-WPAN’s protocol performance for nodes clustering and routing allows the wireless sensor networks to perform nodes clustering based on spatial similarity readings. This paper proposes a firefly-inspired protocol to improve the performance of the protocol in the spatial similarity readings. We call the protocol based on the behavior of firefly as Firefly Inspired Protocol (FIP). The FIP operates to establish the clusters of nodes. The FIP protocol was simulated by NS3 that uses the realistic humidity data to evaluate its performance. The simulation results showed that the clustering protocol could detect robust the anomalous data that was sensed by a node. Furthermore, the protocol was also able to cluster dynamically the nodes that extremely depend on the level of data similarity readings.