System and methods for proactively refreshing portions of a nonvolatile memory including a memory system that proactively refreshes a portion of nonvolatile memory based on data associated with the portion. The data may include the time elapsed since the portion was last refreshed, the number of times the portion has been cycled, and the average operating temperature of the nonvolatile memory. A portion of nonvolatile memory, when meeting certain criteria determined from the data, may be proactively refreshed during a downtime when the nonvolatile memory is not otherwise being accessed.