Study region: Iran's agricultural heartlands, which exist on the precipice of a water crisis that directly endangers national food security and socio-economic stability. Study focus: This study analyzes 30 years of data to assess the effects of meteorological droughts, heatwaves, and their Compound Drought-Heatwave Extremes (CDHEs) occurrences on agricultural water productivity (WP). It evaluates climatic indices to identify the most suitable indicator for WP variability and conducts a spatiotemporal analysis of the intensification of these extremes. New hydrological insights for the region: This study provides a systematic evaluation of how single and compound climate extremes impact agricultural water productivity (WP) in Iran. First, it establishes the Standardized Precipitation Evapotranspiration Index (SPEI-6) as the most robust indicator for capturing WP variability in Iran's arid agroecosystems. Analysis of single extremes reveals a critical divergence: irrigation effectively buffers croplands against meteorological drought, maintaining stable WP, whereas rainfed systems suffer severe WP losses exceeding 20%. Heatwaves alone present a more complex, system-dependent stressor. The investigation of spatiotemporal trends shows that drought, heatwave, and compound event frequencies have intensified significantly over the past 15 years, with emerging hotspots in central Iran and the Zagros Mountains. The most severe hydrological insight, however, concerns Compound DroughtHeatwave Events (CDHEs). These concurrent extremes create a synergistic stress that overwhelms adaptive capacities. While irrigation fails under CDHEs due to unsustainable atmospheric demand, leading to a 13.5% WP decline in irrigated zones, rainfed systems face catastrophic impacts with a 27.4% WP loss. These findings underscore that CDHEs, not single extremes, pose the foremost threat to regional water security, highlighting an urgent need for adaptation strategies that address both water supply and atmospheric demand dynamics.