CHICAGO (CBS) — The brisk start to October is a sharp contrast to September, a month in which the average temperatures were well above normal.

The average high temperature was 78.1 degrees for the month, or 3.3 degrees above normal, according to the National Weather Service.

The average low: 59.8, which is 5.5 degrees above the norm.

Overall the average daily temperature stood at 69 degrees, or 4.4 degrees over what would be typical.

While the end of the month was cooler, the first week was exceptionally warm, with eight consecutive days in the upper 80s or low 90s.

While none of those numbers are a record, Chicago did set one mark: for daily rainfall on Sept. 18, when 2.41 inches fell, nearly a full inch above the old mark of 1.5 inches set in 1907.

Up north in Rockford, it was even warmer: 79.4 average high (up 4 degrees); 58.7 low (up 6.3 degrees); 69.1 overall average (up 5.2). It was the third-warmest September for that city on record, the NWS said.

Forecasters say a strong El Nino–created by warmer Pacific Ocean waters–could mean a warmer, and drier fall and winter for the Chicago area.