<p>Notably, Yunnan Province suffered from extreme spring (March–April) droughts in decaying phase of La Niña and El Niño events in 2023 and 2024, respectively. This is not consistent with previous studies that showed El Niño (La Niña) favors the Yunan drought (flood) in following spring. Our analysis suggests the record-breaking diabatic heating over tropical Indian Ocean plays important roles in the Yunnan spring droughts in these two years, which outweighs the impact of convective heating over central-eastern tropical Pacific. In spring 2024, under the decaying phase of El Niño, there are record-breaking SST warming and diabatic heating over western tropical Indian Ocean (WTIO). Observational analysis and linear baroclinic model (LBM) simulation demonstrate that WTIO diabatic heating can weaken the India-Burma trough (IBT), strengthen western Pacific subtropical high (WPSH), and weaken East Asian trough (EAT), favoring extreme Yunnan drought in spring 2024. In spring 2023, under the decaying phase of La Niña event, record-breaking diabatic heating is over the Arabian Sea-northern Indian Peninsula (ASNI), which is related to the pronounced warming over Arabian Sea. Observational analysis and LBM simulations demonstrate that diabatic heating over ASNI can induce weakened IBT, favoring extreme Yunnan drought in spring 2023. Besides the case study, composite analysis also indicates that the tropical Indian Ocean plays a more important role than the tropical Pacific in Yunnan spring droughts. Further one-month lead dynamical predictions of NCEP CFSv2 and ECMWF SEAS5 indicate that the spring drought in 2024 can be well predicted, due to the models reproduce the observed spring WTIO SST warming and the related-diabatic heating and atmospheric circulations.</p>