A method for warning about lightning activity in wind farms which is suitable for predicting the generation of upward lightning originating from the wind-driven power generators the wind farm and for warning about the possible generation is provided. To that end, in the method the presence or absence of a storm cell in the wind farm and/or in the vicinity thereof, within a radius of less than 400 km, is detected; the local electric field in the wind farm is measured, at least one atmospheric condition is identified or measured under given premises, and the probabilities of the generation of upward lightning originating from the wind-driven power generators of the wind farm are determined depending on the result of the measurements, identifications and detections, a warning signal being transmitted in the event that the determined probability exceeds a given threshold value.