Comparison of accuracy of weather forecast at home and abroad (the data is better) If the accuracy is different, the reason for the gap. thank you

Foreign weather forecasts should also be divided into three or six grades. The weather forecast of developed countries such as the United States is more accurate, but its long-term forecast is not satisfactory because of the complexity of the weather system affecting the United States. However, the prediction accuracy of developing countries and poor countries is not high, and it is still very low in some places.