Wind turbine downtime is particularly costly during winter, for two reasons. First, November to April is the period over which most such plants around the world produce around two thirds of their electricity yield. The wind farms depend on the availability of wind, which in turn depends on the season. Second, logistical costs for maintenance during this time of year are high. So turbine failure at this time must be avoided at all costs. Condition monitoring, perhaps integrated with programmable logic control, can help a plant maintain its energy availability over this crucial period.