EpiGro is a disease outbreak forecasting tool. It started (v.1.0) as a phenonmenological model that described incidence as a quadratic function of the cumulative number of cases. Version 2.0 incorporated the exact definition of the ICC (Incidence – Cumulative Cases) curve for the SIR model, thereby transforming EpiGro into a mechanistic model. Version 3.0, developed for COVID-19 forecasting, combines the mechanistic approach of EpiGro (v.2.0) with variational data assimilation techniques.