Spatiotemporal Characteristics of Heatwave in the Central Region of Bangladesh

Bangladesh, being one of the countries vulnerable to climate change, is also susceptible to heatwave and heat stress alike. This study aims for a comprehensive assessment of the spatiotemporal characteristics of heatwaves in the central region of Bangladesh from 1981 to 2020, based on historical climatic data. Calculated heat indices, using the formula of apparent temperature, characterize heatwave, and categorized into severity-based thresholds based on the National Weather Service (NWS) definition of heatwave, modified accordingly to reflect local climatic variations. Along with the broad spatial distribution of heatwave, this study also explores the seasonal variation of heatwaves through trend analysis and the potential seasonal shifts in the region. Also, evaluating the frequency of severe and extreme heat days through the coefficient of determination and regression analysis provides quantitative insight into predicting future risks. Spatially, in Tangail, Faridpur, and Madaripur, the heatwave events have amplified mainly after the 1990s, while Madaripur exhibits the earliest onset, and Dhaka, in contrast, shows a delay. Summer and monsoon have emerged as the seasons experiencing the most heatwaves throughout the region. The findings also reveal statistically significant intensification patterns in the overall frequency of heat days across the region. The annual severe heat days in regions like Tangail, Faridpur, and Madaripur have been shifting toward extreme heat days in the last decade, with severe days showing a downward trend and extreme days increasing. In contrast, the number of extreme heat days is rising continuously in Dhaka. This pattern reveals a potential risk for the future, suggesting a regionalized approach to deal with the growing heatwave. Both academics and policymakers can benefit from the localized insights this study offers into the features of heatwaves. Future studies should cover a larger geographic area and include a more thorough set of socioeconomic indicators in order to improve the understanding of heatwave risks on a national level.