A method for predicting the accumulation of ice on a rotor blade of a wind turbine , comprising: defining an upper threshold value (So) and/or a lower threshold value (Su) for a system variable (S) which is associated with the mass of the rotor blade and/or with the mass of an ice attachment of the rotor blade ; acquiring system variable data during an acquisition time period (T) for obtaining a curve of the system variable (S) during the acquisition time period (T); carrying out a compensation calculation of the curve profile for a prediction time period (Δt 1 ', Δt 2 ', Δt 3 ') from the system variable data which were acquired during a partial time period (Δt 1 , Δt 2 , Δt 3 ) of the acquisition time period (T) in order to obtain a prediction curve (N1, N2, N3); carrying out at least one further compensation calculation of the curve profile for a further prediction time period (Δt 1 ', Δt 2 ', Δt 3 ') from the system variable data which were acquired during another partial time period (Δt 1 , Δt 2 , Δt 3 ) of the acquisition time period (T) in order to obtain a further prediction curve (N1, N2, N3); determining whether or not the upper threshold value (So) will be exceeded by one or more of the prediction curves (N1, N2, N3) in the future and/or whether or not the lower threshold value (So) will be undershot by one or more of the prediction curves (N1, N2, N3) in the future; and outputting the result of the determination, wherein, if it is determined that the upper threshold value (So) will be exceeded by one or more of the prediction curves (N1, N2, N3) in the future, an ice warning message is output; and wherein, if it is determined that the lower threshold value (Su) will be undershot by one or more of the prediction curves (N1, N2, N3) in the future, a free-of-ice message is output. defining an upper threshold value (So) and/or a lower threshold value (Su) for a system variable (S) which is associated with the mass of the rotor blade and/or with the mass of an ice attachment of the rotor blade ; acquiring system variable data during an acquisition time period (T) for obtaining a curve of the system variable (S) during the acquisition time period (T); carrying out a compensation calculation of the curve profile for a prediction time period (Δt 1 ', Δt 2 ', Δt 3 ') from the system variable data which were acquired during a partial time period (Δt 1 , Δt 2 , Δt 3 ) of the acquisition time period (T) in order to obtain a prediction curve (N1, N2, N3); carrying out at least one further compensation calculation of the curve profile for a further prediction time period (Δt 1 ', Δt 2 ', Δt 3 ') from the system variable data which were acquired during another partial time period (Δt 1 , Δt 2 , Δt 3 ) of the acquisition time period (T) in order to obtain a further prediction curve (N1, N2, N3); determining whether or not the upper threshold value (So) will be exceeded by one or more of the prediction curves (N1, N2, N3) in the future and/or whether or not the lower threshold value (So) will be undershot by one or more of the prediction curves (N1, N2, N3) in the future; and outputting the result of the determination, wherein, if it is determined that the upper threshold value (So) will be exceeded by one or more of the prediction curves (N1, N2, N3) in the future, an ice warning message is output; and wherein, if it is determined that the lower threshold value (Su) will be undershot by one or more of the prediction curves (N1, N2, N3) in the future, a free-of-ice message is output. <EOS>