Harvesting Heat: Agricultural Cycles as Hidden Drivers of Heat Risk

<jats:p>Extreme heat is the deadliest weather-related hazard globally, yet the role of agricultural land management, specifically post-harvest transitions from dense vegetative canopies to exposed bare soil, in amplifying urban heat exposure remains critically unquantified in disaster risk management (DRM) frameworks. This study investigates Land Surface Temperature (LST) dynamics before and after the annual harvest season across seven consecutive years (2020–2026) at the interface between an agricultural plain and the city of Lleida, Catalonia, Spain. Framing the analysis explicitly within the Sendai Framework for Disaster Risk Reduction 2015–2030 , we utilize open-access Landsat 8/9 Collection 2 Level 2 surface temperature products alongside Sentinel-2 Level-2A surface reflectance imagery to derive LST, Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), and Short-Wave Infrared (SWIR) reflectance at a co-registered 20-meter spatial resolution. Across all seven years, post-harvest mean city LST consistently exceeded pre-harvest baselines by 16.4 °C to 38.1 °C, surpassing local emergency thermal risk thresholds in every year evaluated. Strong, spatially co-registered pixel-wise correlations between LST and NDMI (mean r≈-0.74) and LST and NDVI (mean r ~-0.70), along with positive correlations with SWIR (mean r≈+0.74), confirm that rapid loss of canopy moisture and soil evapotranspiration drives severe microclimatic heating beyond natural background summer warming. Since agricultural harvest dates follow highly predictable calendar windows, this phenomenon represents a unique class of predictable spatial hazards. We demonstrate how integrating satellite-tracked agricultural phenology into urban early warning systems and spatial planning directly advances Sendai Framework Priorities 1 and 4.</jats:p>