Lake trophic state modulates the sensitivity of harmful algal blooms to antecedent weather conditions

Cyanobacterial harmful algal blooms (cyanoHABs) are often associated with warm water temperatures and low wind speeds, but quantifying thresholds in meteorological conditions is challenging. Using 4208 cyanoHAB reports from 405 lakes in New York State (USA), we calculated anomalies in daily wind speed and air temperature for each report and the 5 d preceding it. On the day of a cyanoHAB, lakes had lower than average wind speeds and higher than average air temperatures. Notably, the magnitude of these anomalies was influenced by the trophic state of each lake, with nutrient‐limited lakes having larger anomalies on the day of a cyanoHAB. Additionally, the absence of either anomaly type reduced the likelihood of a cyanoHAB, particularly in nutrient‐poor lakes. These results enhance our understanding of the proximate drivers and thresholds regulating cyanoHABs across varying trophic states, suggesting that large‐scale changes in climate may substantially impact future cyanoHAB development.