This thunder hour dataset is combines lightning observations from both Lightning Imaging Sensors (LIS) that operated aboard the International Space Station (ISS) from 1 March 2017 to 16 November 2023 and the Tropical Rainfall Measuring Mission (TRMM) satellite from 1 January 1998 to 8 April 2015. The dataset represents a combined 24 years of observations. The data are provided at 0.05° latitude/longitude resolution for latitudes between 54.75ºS and 54.75ºN. A thunder hour is defined as an hour during which thunder can be heard from a given location. Thunder hours represent a historical measure of lightning occurrence and a metric of thunderstorm frequency that is comparatively less sensitive to geographic variations in the detection capabilities of a lightning location system. Thunder hours are the average number of hours in a given year during which two or more LIS group centroids were observed within 15 km of each grid point. The Combined LIS annual thunder hour dataset is available as a single netCDF-4 file.