The National Weather Study Project (NWSP) is a large-scale environmental study project deploying hundreds of mini weather stations in schools throughout Singapore. In this project, we are developing the National Weather Sensor Grid connecting these weather stations to automatically collect and aggregate the weather data into a Central Data Depository (CDD) in real time. The sensor grid integrates computational and data storage resources for the processing and storage of weather data. We are building tools for publishing, querying, processing, visualizing, archiving and searching the weather data.