OpenMeteoApiNet 1.1.0

OpenMeteoApi.NET

<img src="https://github.com/edrewitz/OpenMeteoApi.NET/blob/master/icons/opem%20meteo%20logo.jpg?raw=true" width="500" alt="Alt text" /> <img src="https://github.com/edrewitz/OpenMeteoApi.NET/blob/master/icons/csharplogo.png?raw=true" width="329" alt="Alt text" />

(C) Eric J. Drewitz 2026

OpenMeteoApi.NET is a C# package that provides an interface with the Open-Meteo API to access various types of weather data.

Current Version:

NuGet Downloads:

Zenodo:

Table of Contents

Documentation

Code Example 1

Code Example 2

Documentation

Forecast Data

NOAA/NCEP Model Data Access

ECMWF Model Data Access

CMC Model Data Access

DWD Model Data Access

Meteo France Model Data Access

Japan Meteorological Agency (JMA)

UK Met Office (UKMO)

Current Analysis

Current Weather

Code Examples

Example 1 OpenMeteoApi.NET Console Application Code

/*
 * In this code example, I will use OpenMeteoAPI.NET to build a basic console application that does the following:
 * 
 * - Retrieves the latest 2-Meter Temperature & 2-Meter Relative Humidity 1-day hourly time series point forecast from the UKMO Global Ensemble.
 * 
 * - Save the forecast data as a CSV file to C:\Users\drewi\Open Meteo Data
 * 
 * - Print the forecast data to the console
 *  
 */

// A using statement in C# is the equivalent of an import statement in Python
using OpenMeteoApiNet.EnsembleForecasts.UKMO.UKMO_Global_ENS;


// The namespace for the Weather Forecast Application
namespace WeatherForecastApplication
{
    class WeatherApp
    {
        // Our main task in our application
        public static async Task Main(string[] args)
        {
            // Continuous loop until the user manually exits the command prompt. 
            while (true)
            {
                // Prompt the user for latitude and longitude

                /* For Python Developers like myself, it is good practice to define variables in C# in the following way:
                 * 
                 * var latitude
                 * var longitude
                 * 
                 * Rather than:
                 * 
                 * double latitude
                 * double longitude
                 * 
                 * This is because using the prefix var allows the compiler to determine the data type (makes it feel dynamically typed like Python)
                 * 
                 */
                // Title
                Console.WriteLine("\nUKMO Global Ensemble Forecast\n");
                Console.WriteLine($"Enter a latitude");
                var latitude = Console.ReadLine();
                Console.WriteLine($"Enter a longitude");
                var longitude = Console.ReadLine();

                // Selects the variables to query: temperature_2m, relative_humidity_2m
                string[] variables = new string[] { "temperature_2m", "relative_humidity_2m" };


                // Retrieve the UKMO Global Ensemble forecast for 1 day
                // Save the data as a CSV file to C:\Users\drewi\Open Meteo Data
                // Retrieves our Microsoft.Data.Analysis DataFrame df
                var df = await ukmoGlobalENSHourlyForecastApi.GetPointForecast(latitude,
                    longitude,
                    variables: variables,
                    days: 1,
                    toCsv: true,
                    filePath: @"C:\Users\drewi\Open Meteo Data");

                // If the Microsoft.Data.Analysis DataFrame is not null proceed to write the output to the console.
                if (df != null)
                {
                    Console.WriteLine("2-Meter Temperature & Relative Humidity Forecast\n");
                    // Prints the Temperature data
                    for (long i = 0; i < df.Rows.Count; i++)
                    {

                        // Print the row data cleanly on a single line
                        Console.WriteLine($"Time: {df["time"][i], -20} | Control: {df["temperature_2m"][i], -6} °F | Member 1: {df["temperature_2m_member01"][i]} °F | Member 10: {df["temperature_2m_member10"][i]} °F |");                        

                    }

                    Console.WriteLine("\n2-Meter Relative Humidity Forecast\n");
                    for (long i = 0; i < df.Rows.Count; i++)
                    {

                        // Print the row data cleanly on a single line                        
                        Console.WriteLine($"Time: {df["time"][i],-20} | Control: {df["relative_humidity_2m"][i],-6} % | Member 1: {df["relative_humidity_2m_member01"][i]} % | Member 10: {df["relative_humidity_2m_member10"][i]} % |");
                    }
                    // Signature and credit
                    Console.WriteLine("\nData Retrieved with OpenMeteoApi.NET (C) Eric J. Drewitz 2026");
                }
                else
                {
                    // Returns this error message to the user if df == null. 
                    Console.WriteLine($"Data not available for (Latitude: {latitude}, Longitude: {longitude}");
                }
            }
        }
    }
}

Example 1 OpenMeteoApi.NET Console Application Output

<img src="https://github.com/edrewitz/OpenMeteoApi.NET/blob/master/examples/OpenMeteoApiNet%20Console%20App.png?raw=true" width="1000" alt="Alt text" />

Example 2 OpenMeteoApi.NET GFS + ECMWF Forecast

/*
 * In this code example, I will use OpenMeteoAPI.NET to build a basic console application that does the following:
 * 
 * - Retrieves the latest 2-Meter Temperature 1-day hourly time series point forecast from the GFS and ECMWF IFS.
 * 
 * - Print the GFS & ECMWF forecasts and the difference between models to the console. 
 *  
 */

// A using statement in C# is the equivalent of an import statement in Python
using OpenMeteoApiNet.DeterministicForecasts.NOAA.GFS;
using OpenMeteoApiNet.DeterministicForecasts.ECMWF.ECMWF_IFS;
using Microsoft.Data.Analysis;

// The namespace for the Weather Forecast Application
namespace WeatherForecastApplication
{
    class WeatherApp
    {
        // Our main task in our application
        public static async Task Main(string[] args)
        {
            // Continuous loop until the user manually exits the command prompt. 
            while (true)
            {
                // Prompt the user for latitude and longitude

                /* For Python Developers like myself, it is good practice to define variables in C# in the following way:
                 * 
                 * var latitude
                 * var longitude
                 * 
                 * Rather than:
                 * 
                 * double latitude
                 * double longitude
                 * 
                 * This is because using the prefix var allows the compiler to determine the data type (makes it feel dynamically typed like Python)
                 * 
                 */
                // Title
                Console.WriteLine("\nGFS & ECMWF IFS 2-Meter Temperature Forecasts\n");
                Console.WriteLine($"Enter a latitude");
                var latitude = Console.ReadLine();
                Console.WriteLine($"Enter a longitude");
                var longitude = Console.ReadLine();

                // Selects the variables to query: temperature_2m
                string[] variables = new string[] { "temperature_2m" };


                // Retrieve the GFS forecast for 1 day as a Microsoft.Data.Analysis DataFrame df
                var gfs = await gfsHourlyForecastApi.GetPointForecast(latitude,
                    longitude,
                    variables: variables,
                    days: 1);

                // Retrieve the ECMWF IFS forecast for 1 day as a Microsoft.Data.Analysis DataFrame df
                var ecmwf = await ifsHourlyForecastApi.GetPointForecast(latitude,
                    longitude,
                    variables: variables,
                    days: 1);

                // Merges our gfs and ecmwf dataframes
                DataFrame df = gfs.Merge(
                                    other: ecmwf,
                                    leftJoinColumns: new string[] { "time" },
                                    rightJoinColumns: new string[] { "time" },
                                    leftSuffix: "_gfs",
                                    rightSuffix: "_ecmwf",
                                    joinAlgorithm: JoinAlgorithm.Left
                                );

                // Drop the column named "time_ecmwf" as this is a redundant field
                df.Columns.Remove("time_ecmwf");

                // Create a new column
                PrimitiveDataFrameColumn<double> temperature_2m_difference = (PrimitiveDataFrameColumn<double>)(df["temperature_2m_gfs"] - df["temperature_2m_ecmwf"]);

                // 4. Name the new column
                temperature_2m_difference.SetName("temperature_2m_difference");

                // 5. Append the new column to the DataFrame
                df.Columns.Add(temperature_2m_difference);

                // If the Microsoft.Data.Analysis DataFrame is not null proceed to write the output to the console.
                if (df != null)
                {
                    Console.WriteLine("\n      Time             GFS      ECMWF     (GFS-ECMWF)");
                    Console.WriteLine("-------------------------------------------------------");
                    // Prints the Forecast data
                    for (long i = 0; i < df.Rows.Count; i++)
                    {
                        // Print the row data cleanly on a single line
                        Console.WriteLine($"{df["time_gfs"][i], -3} UTC | {df["temperature_2m_gfs"][i], -3}°F | {df["temperature_2m_ecmwf"][i],-3}°F | {Math.Round((double)df["temperature_2m_difference"][i], 1),-3}°F");                        

                    }

                    // Signature and credit
                    Console.WriteLine("\nData Retrieved with OpenMeteoApi.NET (C) Eric J. Drewitz 2026");
                }
                else
                {
                    // Returns this error message to the user if df == null. 
                    Console.WriteLine($"Data not available for (Latitude: {latitude}, Longitude: {longitude}");
                }
            }
        }
    }
}

Example 2 OpenMeteoApi.NET Console Application Output

<img src="https://github.com/edrewitz/OpenMeteoApi.NET/blob/master/examples/OpenMeteoApiNet%20ICON%20EPS%20Console.png?raw=true" width="1000" alt="Alt text" />