Do you mean Mean Absolute Error (MAE) and Root mean squared error (RMSE)?

Well, it really depends on your data, model, and the importance of your project. If you are modelling a dry area with low rainfall values then it is different from a wet area. I would say it should not exceed your mean value for sure but I've seen papers which limited the value to 20% of the mean.

Dear attena

What is mad?

Do you mean MAE?

i think that a 25~30% in mean is better relative RMSE