In recent decades, the probability of natural disasters has increased due to climate change. As a result, the discussion of resilience in the power system literature was raised. One consequence of these events is the unwanted operation of some power system equipment, which causes unexpected blackouts and increases the value of energy not supplied (ENS) in the system. Insulators are important components of the power system that have a great impact on the continuity of supply. Electrical flashover in insulators causes a decrease in their insulation strength and might lead to short-circuit faults in the power system. In this paper, the effect of dust storms and humidity on the probability of transmission network insulators flashover is investigated. The studied insulator is simulated in Electrical AutoCAD software, and after applying pollution and moisture in COMSOL-Multiphysics software, the distribution of potential and electric field on the studied insulator is obtained using the finite element method (FEM). In order to determine the probability of insulation flashover, the candidate points for arc occurrence are selected using the roulette wheel method in MATLAB software, and the insulation flashover probability curve is determined in different amounts of dust pollution and three humidity levels of 65%, 80%, and 95%. The effects of increasing the creepage distance and using silicone rubber materials that have hydrophobic properties are investigated, and various sensitivity analyses are conducted. The results indicate that both solutions can significantly reduce the flashover probability of transmission insulators.