Cognitive radio opportunistically utilizes wireless spectrum when licensed user is not present. Accordingly, in cognitive radio, spectrum sensing is an important technique to watch primary user's presence. The sequential spectrum sensing technique considering time varying channel has been discussed in this paper. In sequential sensing technique, current and previous energy observations of cognitive radio hubs are averaged to enhance the spectrum utilization. The moving-normal method applying adaptive weighting has been discussed in this paper. In the event, when the primary user changes it's state, results show that adaptive weighting gives better performance in terms of spectrum utilization by the cognitive radio user.