Heatwaves in Vietnam: Characteristics and relationship with large-scale climate drivers

Abstract

This study analyses the spatio-temporal variability of heatwave characteristics and their association with large-scale climate drivers across seven climatic sub-regions in Vietnam, including the Northwest (R1), Northeast (R2), Red River Delta (R3), North Central (R4), South Central (R5), Central Highlands (R6) and the South (R7). The analysis is based on observed daily maximum temperatures from 102 meteorological stations, spanning the period 1980–2020. The obtained results reveal diverse heatwave patterns across the country. Amongst the seven climatic sub-regions of Vietnam, the R3 and R4 sub-regions experienced more frequent heatwaves and a higher number of heatwave days, but shorter durations. In contrast, other sub-regions had fewer heatwave events and heatwave days but experienced longer-lasting heatwaves. The intensity of heatwave events varies amongst sub-regions, with the highest value in the R4 sub-region, and the lowest in R7. Notably, the R1–R5 sub-regions are affected by heatwaves over larger areas, compared to others. Additionally, the findings confirm that the lagged influence of El Niño–Southern Oscillation (ENSO) is the primary climatic driver of heatwave characteristics in Vietnam. Generally, heatwaves tend to occur more frequently in the years following El Niño events than after La Niña events. This observation provides opportunities for developing a system of seasonal predictions of heatwaves in Vietnam. The impact of ENSO on the number of heatwave events and heatwave days is evident in five out of seven sub-regions, with less impact in the R2 and R7 sub-regions. However, it does not significantly affect heatwave intensity.