Over the years, integrated remediation efforts in Lake Dianchi have yielded significant interim success in curbing cyanobacterial blooms. From 2018 onward, both the frequency and spatial extent of these blooms showed a consistent downward trend. However, a marked resurgence was observed in 2023, prompting renewed scientific and public concern. This study systematically investigates the variability and outbreak mechanisms of cyanobacterial blooms in Lake Dianchi from 2018 to 2023, leveraging MODIS satellite imagery alongside integrated water quality and meteorological monitoring data. Analysis of the monitoring data reveals that the annual bloom frequency followed a “V”-shaped trajectory over the six-year period, with 2023 registering a notably high frequency of 87.0%, significantly exceeding the six-year average of 69.3%. In contrast, the average bloom area from 2022 to 2023 was substantially lower than that from 2018 to 2021. Specifically, the average bloom area in 2023 (15.86 km²) was 65.3% below the six-year mean, although it represented an 11.4% increase from 2022. Spearman correlation analysis demonstrated that both monthly bloom frequency and monthly average bloom area were significantly positively correlated with monthly average temperature and monthly precipitation, while showing a significant negative correlation with monthly average wind speed. Additionally, the monthly average cyanobacterial density exhibited a strong positive correlation with the monthly average total phosphorus concentration. Multivariate linear regression analysis highlighted air temperature and wind speed as the dominant meteorological drivers of bloom dynamics in Lake Dianchi. However, total phosphorus concentration had limited explanatory power regarding variations in algal density. Throughout the 2018-2023 period, cyanobacterial density consistently surpassed the mild bloom threshold (1.0×107 cells/L), suggesting that the 2023 resurgence was primarily driven by synergistic meteorological influences. During the non-bloom season (January-May and December), an increased proportion of temperatures between 13-20 ℃ accelerated cyanobacterial resurgence. During the bloom season (June-November), the increase in the proportion of low wind speeds (＜2 m/s) promoted cyanobacterial surfacing and aggregation. A reduced proportion of temperatures below 13 ℃ favored cyanobacterial growth. A significant rise in the proportion of 20-25 ℃ temperatures during the bloom season likely enhanced cyanobacterial buoyancy, contributing to the broader bloom coverage observed in 2023. These findings offer valuable theoretical support for the daily prevention, prediction, and early warning systems for cyanobacterial blooms in Lake Dianchi. Furthermore, they provide a reference for bloom management in other plateau lakes across Yunnan Province.