1. A computer-readable recording medium that stores therein a computer program that causes a computer to execute: computing a predicted value indicative of weather at a plurality of time points from a first time point in the past with respect to each initial value; acquiring actual values actually observed at each of the time points; comparing the predicted value at any specific time point with an actual value at the specific time point and determining whether a difference between the predicted value and the actual values is within a tolerance; repeating the comparing for all the time points; and deleting those initial values for which it is determined at the comparing that the difference is out of the tolerance; and substituting remaining initial values into a weather prediction model for performing weather prediction at a second time point in future.