Secondary users, in most present spectrum decision schemes, usually endeavored to avoid coexisting with primary users, at the expense of some spectrum resources and handoff latency. Interference temperature model which allowed simultaneous communication between secondary users and primary users solved this problem. A new metric called outage probability was proposed for the spectrum handoff under interference temperature limits in cognitive wireless mesh networks. Furthermore, the policy was applied to the probability-based spectrum decision strategy. Simulation results show that the proposed decision scheme reduces the outage probability and overall transmission time of secondary users, simultaneously guarantees the fairness in the channel utilization, and further improves the network performance.