This study analyzed the cost of wind uncertainty by estimating the impact of various degrees of wind uncertainty on theoperating cost of a power system. For the analysis methodology, this study used a simulation applying a stochastic form ofsecurity-constrained optimal power flow (SCOPF) based on the Jeju power system. To generate realistic wind generation input, a windforecasting model based on an econometric time-series method was proposed in four major wind farms in Jeju Island. The resultshowed that the case with the deterministic wind reduces the operating cost most effectively. On the other hand, when the system facesstochastic wind forecasted 1 hour ahead, the amount of reserve required increases significantly. In addition, when the degree of winduncertainty increases as the system operator conducts the day-ahead planning with the stochastic wind forecasted 4 hours ahead and 7hours ahead, the amount of reserve required increases further and the amount of wind generation that the power system could adoptdecreases, which leads to an increase in the overall operating cos