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Previous studies have observed seasonal cooling effects in paddy rice as compared to temperate forest through enhanced evapotranspiration (<i>ET</i>) in Northeast Asia, while rare studies have revealed biophysical factors responsible for spatial variations of <i>ET</i> and its cooling effects. In this study, we adopted a data fusion method that integrated MODIS 8-day surface reflectance products, gridded daily climate data of ground surface, and a remote sensing pixel-based Penman-Monteith ET model (i.e., the RS–PM model) to quantify ET patterns of paddy rice in South Korea from 2011 to 2014. Results indicated that the regional variations of the rice-growing season <i>ET</i> (<i>RGS-ET</i>, the sum of daily <i>ET</i> from the season onset of rapid canopy expansion (<i>SoS</i>) to the end of the rice-growing season (<i>EGS</i>)) were primarily influenced by phenological factors (i.e., the length of growing period-<i>LGP</i>), followed by growing season mean climatic factors (i.e., vapor pressure deficit-<i>VPD</i>, and air temperature). For regional variations of the paddy field <i>ET</i> (<i>PF-ET</i>, the sum of daily <i>ET</i> from the field flooding and transplanting date detected by satellite observations (<i>FFTD</i>_sat) to <i>SoS</i>, and to <i>EGS</i>), the extents were substantially reduced, only accounting for 54% of the <i>RGS-ET</i> variations. The <i>FFTD</i>_sat and <i>SoS</i> were considered critical for the reduced <i>PF-ET</i> variations. In comparison to the temperate forest, changes in monthly ground surface air temperature (<i>T</i>_s) in paddy fields showed the V-shaped seasonal pattern with significant cooling effects found in late spring and early summer, primarily due to a large decline in daytime <i>T</i>_s that exceeded the nighttime warming. Bringing <i>FFTD</i>_sat towards late spring and early summer was identified as vital field management practices, causing significant declines in daytime <i>T</i>_s due to enhanced <i>ET</i>. Results highlighted climate-warming mitigation by paddy fields due to early flooding practices.