We present a 25-year data record of cloud base height measured by ceilometer at the Ny-Ålesund, Svalbard, Arctic site. The long-term time series allows derivation of an annual cycle of the cloud occurrence frequency, revealing more frequent cloud cover in summer and the lowest cloud cover amount in April. The cloud base data further provide essential information for the interpretation of the surface radiation balance and contribute to understanding meteorological processes at high latitudes.