With the current developments of numerical weather forecasting technology and seasonal prediction systems,the ability of short-term weather forecast and long-term climate prediction continues to improve.However,the prediction skill of the subseasonal to seasonal(S2S,two weeks to three months) system is relatively weak,and this has become a challenging issue for the meteorological community and operational services.In 2012,the research team led by Prof.Tim Li at Nanjing University of Information Science & Technology developed the spatial-temporal projection model (STPM).The STPM exhibits high skill in predicting the rainfall and temperature anomalies and extreme events in China,such as extreme precipitation,heatwave,extreme cold days and typhoon clustering events,at the lead time of 10 to 30 d.Real-time extended-range weather forecast have been carried out using the STPM at the National Climate Center and in several provinces.In addition to the subseasonal forecast,the STPM has also been successfully applied to the forecasts of spring rain in Taiwan,the onset of the South China Sea monsoon and ENSO.In the present paper,we introduce the physical basis of S2S prediction and the development and application of STPM,and discuss the challenges and future prospects of S2S prediction.