In the context of frequent extreme weather events, ensuring the safe and stable operation of power systems with a high share of new energy faces enormous challenges, and deploying energy storage is key to improving the power grid’s resilience to extreme weather. This paper proposes an energy storage configuration method that accounts for extreme ramp events. First, a criterion is introduced for sustained low output of high-renewable-penetration power systems under extreme weather conditions, and a planning strategy for mitigating system imbalance risk under these circumstances is developed. Next, typical-day and extreme-day scenarios are jointly considered to establish an energy storage optimization configuration method for high-renewable-penetration power systems that considers extreme ramp events. Finally, simulation results on the New England 10-machine 39-node system show that, compared with conventional methods that do not take extreme scenarios into account, the proposed method can reduce load loss risk in high-renewable-penetration power systems under extreme weather, exhibiting both lower load loss risk and enhanced safety and stability.