Power production of wave energy converters (WEC) predicted in the time domain use wave resource parameters and time-domain hydrodynamic model simulations that provide high temporal resolutions (10s of Hz). However, wave resource parameters are often based on frequency-domain calculations with temporal resolution of 30 min to an hour. Real ocean wave conditions vary on much shorter time scales. Relying on frequency-domain calculations will not be sufficient to capture short-term variability and accurately predict WEC power production for a standardized methodology that follows power system requirements. Low temporal resolution data sets are being used in a majority of studies to generate representative wave conditions as inputs to numerical simulations by generating wave spectra. Spectra are then used to predict the efficiency of systems that will not accurately capture the variability of waves in short timeframes. Creating a standardized methodology to increase the temporal resolution of metaocean conditions to inform model development can provide better power production forecasting. In this paper, random amplitude, Fourier coefficient methods have been used for WEC simulations of finite durations to improve the observed variability in wave heights and power production. Variability using this method does increase for finite durations compared to the commonly used deterministic amplitude method.