With the recent surge in deploying aerial Optical Ground Wires (OPGW) as the infrastructure of optical networks, there is a challenging problem which is related to lightning strikes and their effect on the State-of-Polarization (SOP) experienced by dual-polarization coherent receivers. In network planning, all factors that concern the transporting traffic should be taken into consideration. When performing network planning, Routing and Spectrum Assignment (RSA) algorithms that use cost functions are invoked. We propose a cost function, for optical networks with OPGW links, that contains risk factor and meteorology information to reduce the impact of lightning strikes on live traffic.