NOAA released their summary for the climate of September 2015 today. The analysis shows that this September was the second warmest since records began in 1895, following September 1998, which was the warmest September on record. Most of the country was warmer than normal, but the Southeast was very close to the long-term average and thus relatively cooler than most of the country.
Precipitation was less than normal in the majority of the lower 48 states, with the wettest area in the Northeast. Most of the Southeast, with the exception of northern Alabama, was near or above normal in rainfall.
You can read the full summary at https://www.ncdc.noaa.gov/sotc/summary-info/national/201509.
