European Centre for Medium-Range Weather Forecasts (ECMWF). The ECMWF is a European organization that produces some of the world’s most accurate weather forecasts. It specializes in predicting the weather up to two weeks ahead and also provides data on climate and air quality. Based in Germany, Italy, and the UK, it supports the EU’s Copernicus Programme, helping governments, businesses, and researchers better understand and prepare for changes in weather and climate.