The NOAA Coral Reef Watch (CRW) daily Single-Day Bleaching Stress Extent (Alert Level 2 or Higher) product summarizes the spatial extent of the heat stress across coral reef locations experienced on a single day that is presented as the daily Single-Day Bleaching Alert Area. The product is presented in two versions of two-panel time series figures: 2020–present (for most recent years, top figure) and 1986–present (for the entire time series, bottom figure). Each of the two figures shows the time series of daily percentages of 5 km reef-containing pixels within each of the three tropical ocean basins (Pacific, Atlantic, Indian; top panel) and globally (bottom panel) experiencing bleaching-level heat stress (Bleaching Alert Level 2 or higher). Data and figures are updated daily.

At Alert Level 1 of Coral Reef Watch's bleaching heat stress alert system, accumulated stress has reached levels associated with a risk of widespread coral bleaching. This product provides a measure of the geographic footprint of ecologically relevant heat stress. At Alert Level 2, accumulated stress has reached levels associated with a risk of Reef-Wide Bleaching with Mortality of Heat-Sensitive Corals.