In this paper we propose to create an Arduino based weather forecasting system using various sensors. The objective of this paper is to present to you a portable weather monitoring and rain forecasting system. Weather refers to the conditions of the atmosphere by measuring day to day temperature changes and describes various attributes of the troposphere [1]. While climate refers to an average over vast ranges of time [2]. With advancement of technology the act of automating weather monitoring is not only possible but also beneficial. This system will be of interest and use to weather enthusiasts and companies or individuals whose work depends on weather conditions. For example this system will be helpful in agriculture for monitoring the weather and giving warnings when the weather conditions become adverse to the planted crops. Some sports depend specifically on the weather and this system can be used for aiding sportsmen who participate in such sports.