A wind resource assessment is initiated as part of the decision process leading to selecting a wind farm site. ere are multiple factors that inuence site selection. Among them are legal considerations, community opinion, ease of construction, maintenance, and cabling cost. Arguably, most crucial is whether there is enough wind in the ideal speed range that will endure over a long span of time, such as a generation or longer. Prediction of wind at high frequency, such as hours to days to weeks, is fraught with technical and sensing challenges-plus intrinsic uncertainty. Wind resource assessment for site selection contrasts with high frequency prediction. Its goal is to provide a general estimate that guides selection without being a precise prediction. e annual, actual wind resource of a farm would be expected to deviate from the assessment with reasonable variance. However, when the actual annual resource is averaged over a long time span, the goal is that assessment and actuality should match up. In this way, wind resource assessment helps inform the question of the production capacity of the site over its extended lifetime (which potentially includes successive upgrades of turbines and related facilities).