For the FED to raise rates in September, growth in the US economy would need to clearly show up in the economic data. Inflation numbers were not really there given the strong US Dollar (imports are cheaper) and low oil prices (commodity price slump). Additionally, the employment figures were not strong across the board. Therefore, based on solely economic data, there was a good chance that the FED would not raise rates.
With the Chinese stock market meltdown, the chance of a rate rise has been reduced significantly. Now there is additional uncertainty and risk. How much will other emerging markets be affected by the slowdown in Chinese growth?
Therefore, I think the rate rise will be delayed.