1. A method of predicting wind speed at one or more target sites comprising the steps of: measuring wind speed and direction at one or more meteorological towers at said one or more meteorological towers; defining the location or locations of said one or more target sites at which wind speed is to be predicted; calculating exposure, using a computer, at said one or more meteorological towers; calculating terrain complexity using a computer; selecting a wind flow model based on said terrain complexity wherein said wind flow model relates change in wind speed to change in exposure; calculating exposure at said one or more target sites and calculating the difference in exposure between said one or more meteorological towers and said one or more prospective wind turbine sites; and applying said wind flow model using the wind speed at said one or more meteorological towers and said difference in exposure between said one or more meteorological towers and said one or more target sites to predict a wind speed for said one or more target sites.