We develop load balancing algorithms for WDM-based packet networks where the average traffic between nodes is dynamically changing. In WDM-based packet networks, routers are connected to each other using wavelengths (lightpaths) to form a logical network topology. The logical topology may be reconfigured by rearranging the lightpaths connecting the routers. Our algorithms reconfigure the logical topology to minimize the maximum link load. In this paper, we develop iterative reconfiguration algorithms for load balancing that track rapid changes in the traffic pattern. At each reconfiguration step, our algorithms make only a small change to the network topology hence minimizing the disruption to the network. We study the performance of our algorithms under several dynamic traffic scenarios and show that our algorithms perform near optimally. We further show that these large reconfiguration gains are achievable in systems with a limited number of wavelengths.