Sorry, But need much more detail. For example, what do you mean by bias - inaccuracy or imprecision, what precisely are you trying to forecast (mean, range, ...), what data do you have, what is the model you are using, what is the scale at which you are working in space and time.; is it for one place or multiple places; how do you know the current results are biased?
Is this relevant
Article Statistical bias correction for daily precipitation in Regio...
or this
Article Bias correction of monthly precipitation and temperature fie...