The ability of wind power to reliably contribute energy to electricity networks is directly related to the characteristics of the wind resource. An analysis of the characteristics of the wind power resource of the United Kingdom has been carried out, based on modelling of hourly observed wind speed data from 66 onshore weather recording sites for the period 1970-2003. Patterns of wind power availability are presented, with the data demonstrating that the output from large-scale wind power development in the UK has distinct patterns of monthly and hourly variability. The extent and frequency of high and low wind power events is assessed, and wind power data are matched with electricity demand data to examine the relationship between wind power output and electricity demand. It is demonstrated that wind power output in the UK has a weak, positive correlation to current electricity demand patterns; during peak demand periods, the capacity factor of wind power in the UK is around 30% higher than the annual average capacity factor. Comments on the relevance of these findings to modelling the impact of wind-generated electricity on existing electricity networks are given. (c) 2005 Elsevier Ltd. All rights reserved.