This study utilizes Heatwave Intensity-Duration-Frequency (HWIDF) curves to investigate the relationships among intensity, duration, and frequency of heatwave events across six climatic zones in India: Arid, Semiarid, Montane, Humid Subtropical, Tropical Wet, and Tropical Wet & Dry. Using observational data from the Indian Meteorological Department (IMD) and MRI-ESM2-0 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we assess changes in heatwave intensities across varying return periods under both anthropogenic and natural conditions. Our analysis reveals that the Arid zone experiences the highest heatwave intensities, with a duration of one to ten days, with maximum and average values of 44.32 degrees C and 36.56 degrees C, respectively, for two-year return periods. Notably, the Humid Subtropical zone shows a significantly increased likelihood of extreme heatwaves compared to other zones, while the Montane zone exhibits a lower likelihood. Furthermore, historical conditions, which include anthropogenic factors, present a higher risk of intense heatwaves over consecutive five- and ten-day periods compared to natural conditions. These findings underscore the influence of human-caused warming on the increasing frequency and severity of heatwaves. This study emphasizes the necessity for targeted climate adaptation strategies, particularly in vulnerable zones, to mitigate the impacts of climate change on heatwave characteristics.