There is provided a removable chromatic witness assembly, system, and method to monitor thermal events and impact events on a surface of a composite structure. The removable chromatic witness assembly has a plurality of chromatic witness geometric configurations separately coupled in an arrangement to one or more portions of a polymeric film layer. Each chromatic witness geometric configuration has a plurality of chromatic probes of a same type incorporated into an adhesive material. At least two of the geometric configurations have a different type of chromatic probes with a different sensing capability for thermal events and impact events on the composite structure. The polymeric film layer and the geometric configurations form the removable chromatic witness assembly in a form of a removable chromatic witness applique configured to be removably applied directly and continuously to the surface of the composite structure, and configured to monitor the thermal and impact events.