Imagine you had an 'infinitely' powerful computer and you knew the temperature, humidity, density, pressure and wind direction of every cubic centimeter of the atmosphere on earth and you fed this info into the computer - which had a 'perfect' program. That would allow you to predict the weather for the next day with near perfect results. The prediction of what the weather would be in 2 weeks would drop to about 50% accuracy. Why? Becasue the weather is an inherently chaotic system. Even though the system is chaotic in nature you can still make very accurate predictions about the general aspects, such as winter will be colder than summer. Ironically enough, the average temperature in Febuary here was warmer than March. Chaotic indeed.