GribApi.NET is a C# library for reading and writing GRIB 1 and 2 files. It wraps the European Centre for Medium Range Weather Forecasting's powerful C library, ecCodes. NOTE: This library requires the 2015 MSVC redistributable package (https://www.microsoft.com/en-us/download/details.aspx?id=48145)
openweathermap based .NET api
please see more info here https://github.com/awesomio/Weather.NET
Simple .NET Weather API, currently gets the current weather and One Call API
Class library implementing advanced mathematical algorithms, transforms, and time series manipulations. Implementations favour simplicity and correctness.