Proper level of withering plays an important role in overall quality of the produced tea. Withering is the first process in tea manufacturing and is considered the foundation of quality tea. In this paper, an in-situ instrumentation technique is proposed, which is validated experimentally for monitoring of parameters affecting the withering process of tea leaves in black tea production. In the proposed technique, distribution of relative humidity and temperature during withering process is monitored and recorded which would be useful for prediction of withering level using advanced soft computing tool. The implementation detail of a sensor network is presented in the paper. Using the sensor network, variations in the distribution of relative humidity and temperature in a withering trough is monitored and recorded.