Using Landsat and Moderate-resolution Imaging Spectroradiometer (MODIS) satellite data, cyanobacteria bloom initiation dates over two decades (1987-2011) in Lake Taihu showed three distinct trends. Initial blooms occurred later each year between 1987 and 1997 and then generally earlier until 2007, when the earliest and most extensive blooms occurred. After 2007, bloom initiation dates occurred later each year. Climate and catchment control over bloom dynamics was observed, in particular winter temperature minima and nutrient ratios. © 2014 The Author 2014.