A model of atomization and evaporation of a transient spray is presented. This model includes several submodels. The submodel for the primary atomization of the spray core is based on the jet interface instabilities caused by aerodynamic action and includes an intact length model. The droplet secondary atomization is modelled by means of the Taylor analogy. A submodel of droplet evaporation has been developed, in which a heat-up or transient period and a steady state are taken into account, as well as convection effects. Finally a submodel of the droplet deceleration caused by the aerodynamic action due to the air-droplet relative velocity is included. The model is adjusted with the data obtained with a two component Phase-Doppler Anemometer in a test facility with variable air temperature (at atmospheric pressure) in which a Diesel spray is injected.