In some ways, predicting the economy is even more difficult than forecasting the weather, because an economy is not made up of molecules whose behavior is subject to the laws of physics, but rather of human beings who are themselves thinking about the future and whose behavior may be influenced by the forecasts that they or others make.
To be sure, historical relationships and regularities can help economists, as well as weather forecasters, gain some insight into the future, but these must be used with considerable caution and healthy skepticism. In planning our own individual lives, we all have a strong psychological need to believe that we can control, or at least anticipate, much of what will happen to us.