The current state of the art and dedicated applications in Early Warning Systems (EWS) of hydrological and meteorological threats are presented herein. Special emphasis is placed on systems based on the post-processing of deterministic numerical weather forecasts in the real-time mode. The importance of climate and weather forecasting models in providing warnings against slow and rapid onset rates e.g. drought and dispersion of atmospheric pollutants respectively, is discussed. It is strongly suggested that there is a need for systems, corresponding to crisis situations in the field of environmental hazards and/or human activities in general, that would be able to provide support and information about further possible scenarios with a projected state of both the environment and the possibility of the negative impact of various factors on the population (human communities). Since there are highly developed plans for the construction of a nuclear power plant in Poland, there is an urgent need to prepare adequate tools that will help avoid crisis situations, or at least to minimize their negative effects. The Early Warning System should be considered one such tool, to be used not only for its economic benefits, but also for pro-social areas of services responsible for the appropriate reaction to crisis events.