Weather statistics for the Month of September in Atlantic, show the month was much wetter, and slightly warmer than normal. Data compiled at the KJAN Studios (The official National Weather Service reporting station), show rainfall for the month, which is normally 3.81 inches, amounted to 8.82 inches, or nearly 5 inches above average. The average High last month was 81, which was about 5 degrees warmer than normal, and the average Low was 58, or about a little more than 7 degrees above normal. In October, we typically receive 2.76 inches of rain. The average High is 64.1, and the average Low is 39.