A performance anomaly detector obtains a performance metric value from a performance measurement of operation of a resource, and determines a modified Z-score based on the. Occurrence of an anomaly event for the resource is detected responsive to determining that: 1) the modified Z-score exceeds a Z-score anomaly threshold; and 2) a threshold number of other modified Z-scores, which are determined for the other performance metric values in the sequence and are within a sequence window range of the performance metric value, also exceed the Z-score anomaly threshold. A remedial action for the resource is initiated responsive to detecting the occurrence of the anomaly event for the resource.