Based on the largescale synoptic pattern analysis, we found that the key reason that caused abnormal heat waves in the winter in northern areas of Viet Nam is due to the unusual activities of western hot low pressure and western Pacific subtropical high pressure in combination with “foehn” effect caused by Hoang Lien Son high rock mountain . In some cases, the combination between strong cold surge that descending from the south China and western hot low pressure also caused an abnormal heat wave in the winter. | Study on a case study of abnormal heat waves in the winter in the northern areas of Viet Nam in 2010 and 2015
