The LIS/OTD 2.5 Degree Low Resolution Annual Climatology Time Series (LRACTS) consists of gridded climatologies of total lightning flash rates seen by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS). The long LIS (equatorward of about 38 degree) record makes the merged climatology most robust in the tropics and subtropics, while the high latitude data is entirely from OTD. The LRACTS dataset include annual flash rate time series data in MP4 format.