An open-front refrigerated display case is provided having a medium temperature zone disposed above a low temperature zone in a generally vertically-stacked arrangement. A spillover airflow-diverting device is disposed between the medium temperature zone and the low temperature zone and is configured to direct spillover air from the medium temperature zone air curtain (and ambient air entrained therewith) in a direction away from the open front of the low temperature zone. The spillover airflow-diverting device may include louvers configured to direct a gravity-induced flow of the spillover air in an outward direction away from the open front of the low temperature zone, or may include fans to collect spillover air and forcibly direct it in an outward direction away from the open front of the low temperature zone. The outwardly directed spillover air may be discharged in the form of an ‘outer layer’ for an air curtain on the low temperature zone.