Site Classification: Multiple thermal parameters were calculated at different temporal resolutions and examined across thirteen lagoonal reef sites. Lagoonal reefs are located between the barrier reef’s crest and the mainland, and therefore do not include the seaward facing fore-reef. Instead, lagoonal reefs include nearshore reefs, patch reefs, and the back reef. Four thermal parameters produced distinct environments for the reef sites across the Belize MBRS: average annual maximum temperature, average annual temperature range, average annual number of days above the regional bleaching threshold of 29.7°C, and average annual consecutive days above the regional bleaching threshold (i.e., longest potential thermal stress events). A metric that combined all four thermal parameters was generated using ArcGIS in order to assess thermal environments across the Belize MBRS. Data from each of the four parameters in the metric were divided into 8–10 bins (0.5 standard deviations (SD) of the mean) and overlaid on a map of the Belize MBRS. Reefs were not present in areas where the value of any single variable was <1 SD below or >2 SD above the mean (across the entire data set from 2003–2012). For all four parameters, areas that were classified in bins ≥1 SD above the mean were designated high temperature parameter (highTP) sites. Moderate temperature parameter (modTP) sites were classified as areas where all values were 0.5 to 1 SD above the average annual temperature range and the average annual maximum temperature, and within 1 SD of the average annual consecutive days and the average annual number of days above the regional bleaching threshold. Low temperature parameter (lowTP) sites were classified as bins that were 0.5 SD above the average to 2 SD below the average for annual temperature range and annual maximum temperature, and below the average for consecutive and annual days above the regional bleaching threshold. Using the metric presented in Fig. 1, Baumann et al (2016), fifteen sites were identified, thirteen of which were visited and surveyed in November 2014 (the two northernmost highTP sites were not surveyed as corals were not located within the marked geographic area).