Integrated Pest Management (IPM) strategies have acquired importance under the plant protection umbrella, butthey are found wanting in terms of utilization of weather based information that can improve their efficacy by many folds. Themost sensible approach is to make the best use of knowledge on meteorological influence on the incidence of insect pests foradoption of suitable management practices. In order to reduce the losses, the farmers need to be informed regarding theprevailing weather and forewarn the farmers about the impending weather, its effect on pest incidence and for implementationof management operations. The importance of a weather based forewarning models of insect pests can be emphasized only byits ability to forecast their attack well in advance to plan for implementation of the management schedules. It providessufficient time to the farmers to get prepared for taking action against insect pests which reduces the cost of production andserves as prerequisite to IPM. Nationwide projects on development of weather-based forewarning system for different cropswas started under NATP for different agro-climatic zones. AICRP on Agro-meteorology and some of the State AgriculturalUniversities/ Institutes are being involved in developing the models. The main requirements for developing pest forecastingmodels are data on weather parameters, pest population, natural enemies and crop phenology. Pest weather calendars are alsoprepared by using these parameters. The developed prediction/ forewarning models of various insect pests in different agroclimaticzones on field and horticultural crops have been presented and discussed in this paper.