AgStack Weather Server is a backend service for ingesting, preprocessing, and serving historical weather data relevant to agricultural applications. It supports API-based access to weather histories by location, delivering clean, tabular data sourced from multiple datasets, including Multi-Sensor QPE, NLDAS-2, and NOAA archives. The system handles data resolution, substitution for missing values, and grid-based spatial processing to deliver high-quality weather information where possible. It is designed for integration into agricultural platforms that require localized climate data for decision-making.