Readings were taken once every hour from temperature loggers (HOBO Pendant model UA-002-64, Onset), that were attached to each reef. Loggers were deployed on the shallow forereef (around 4-5 m deep) to capture temperature/light during a 120 day summer period (around Dec 2014-May 2015) and winter period (July-October 2015), as part of a wider experiment to understand coralline algae calcification. Eighteen coral reefs were targeted (labelled A-R) as part of a latitudinal/cross-shelf experimental design. Three replicate reefs, spaced at least 1 km apart in the Northern inner-shelf (Turtle Group), Northern midshelf (Lizard Island), Central inner-shelf (Palm Islands), Central midshelf (Rib and Bramble Reefs), Southern inner-shelf (Keppel Islands) and Southern midshelf (Heron and Wistari Reefs).