Spatiotemporal Dynamics of Heatwave Hazards and their Influence on Boro Rice Yield in Northwestern Bangladesh

Abstract

During the Boro rice season, heatwaves have the potential to increase the thermal stress and influence the rice sustainability in northwestern Bangladesh. This study assessed the spatial and temporal patterns of Boro-season heatwaves using daily maximum temperature data from six Bangladesh Meteorological Department stations during 2000–2024. The station-specific 90^th percentile of maximum temperature and 3-days or more consecutive days were used to determine heatwaves. Frequency was computed per station, and inverse distance weighting interpolation was applied to map spatial hotspots. The interpolated surface was used to estimate the station-wise mean heatwave frequency and categorized into the hotspots. Boro rice yield data of 2007-2024 of Rajshahi district was also assessed based on case. The findings indicated evident spatial differences in the frequency of heatwave, with Rajshahi (10.72 days/year) recording the highest mean annual frequency, then Ishwardi (9.92 days/year), and Rangpur with the lowest frequency (8.44 days/year). Southwestern regions, particularly Rajshahi and Ishwardi, emerged as intensity hotspots. The number of heatwave days per year was found to be highly interannual with an increasing trend of about 2.02 days/year. The yield evaluation in Rajshahi revealed that the frequency of a heatwave had a weak correlation with the yield of Boro rice (R²=0.07), indicating that there are numerous climatic and management variables affecting yield variability. The results demonstrate the necessity of the localized heat-risk control, the enhanced irrigation planning, and the heat-resistant rice types in the hotspots regions.

SAARC J. Agric., 24(1): 217-234 (2026)