The Center for Integrated Space Weather Modeling (CISM) has developed three forecast models (FM) for the Sun-Earth chain and matured two of them close to the operational stage. The Sun-Earth chain comprises empirical and physical models: the Planetary Equivalent Amplitude (AP_FM), the Solar Wind (SW_FM), and the Geospace (GS_FM). We give a brief overview over these forecast models and discuss the associated validation studies. We also demonstrate the utility of the models: AP_FM supporting the operations of the AIM mission soon after launch, SW_FM providing assistance with the interpretation of the STEREO Beacon data, GS_FM combining model and observed data to characterize the aurora borealis.