Climate Summary for September 2012; First Month Cooler than Normal in a Year at Chicago

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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
810 AM CDT MON OCT 1 2012

...A LOOK BACK AT THE CLIMATE FOR THE MONTH OF SEPTEMBER 2012 FOR
CHICAGO AND ROCKFORD...

AT CHICAGO...THE AVERAGE HIGH TEMPERATURE WAS 74.5 DEGREES WHICH IS
0.3 DEGREES BELOW NORMAL. THE AVERAGE LOW TEMPERATURE WAS 53.7
DEGREES WHICH IS 0.6 DEGREES BELOW NORMAL.  THE AVERAGE TEMPERATURE
FOR THE MONTH WAS 64.1 DEGREES WHICH IS 0.5 DEGREES BELOW NORMAL.
1.76 INCHES OF PRECIPITATION WAS RECORDED WHICH IS 1.45 INCHES BELOW
NORMAL.

NO RECORDS WERE SET OR TIED AT CHICAGO FOR THE MONTH OF SEPTEMBER.

AT ROCKFORD...THE AVERAGE HIGH TEMPERATURE WAS 76.4 DEGREES WHICH
IS 1.0 DEGREE ABOVE NORMAL.  THE AVERAGE LOW TEMPERATURE WAS 49.5
DEGREES WHICH IS 2.9 DEGREES BELOW NORMAL.  THE AVERAGE TEMPERATURE
FOR THE MONTH WAS 62.9 DEGREES WHICH IS 1.0 DEGREES BELOW NORMAL.
1.74 INCHES OF PRECIPITATION WAS RECORDED WHICH IS 1.61 INCHES BELOW
NORMAL.

NO RECORDS WERE SET OR TIED AT ROCKFORD FOR THE MONTH OF SEPTEMBER.

$$

PUBLIC INFORMATION STATEMENT...CORRECTED ROCKFORD DATA
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
407 PM CDT TUE OCT 2 2012

...STRETCH OF ELEVEN CONSECUTIVE MONTHS WARMER THAN NORMAL COMES TO
AN END AT CHICAGO...

AN IMPRESSIVE STRETCH OF CONSECUTIVE MONTHS WARMER THAN NORMAL HAS
ENDED AT CHICAGO. SEPTEMBER 2012 FINISHED 0.5 DEGREE BELOW NORMAL AT
CHICAGO AND 1.0 DEGREE BELOW NORMAL AT ROCKFORD. FOR CHICAGO...THIS
WAS THE FIRST MONTH COOLER THAN NORMAL SINCE SEPTEMBER OF LAST YEAR.
ROCKFORD ACTUALLY FINISHED AUGUST 2012 JUST UNDER NORMAL FOR THE
MONTH...AT 0.1 BELOW DEGREES BELOW NORMAL...ENDING A STRETCH OF TEN
CONSECUTIVE MONTHS WITH ABOVE NORMAL TEMPERATURES THERE. THUS
SEPTEMBER 2012 WAS THE SECOND CONSECUTIVE MONTH AT ROCKFORD WITH
BELOW NORMAL TEMPERATURES.

CHICAGO...

THE ELEVEN MONTHS IN A ROW WARMER THAN NORMAL WAS THE LONGEST
SUCH CONSECUTIVE MONTHLY STRETCH ABOVE NORMAL IN CHICAGO SINCE THE
EARLY 1920S. THAT STRETCH WAS A REMARKABLE 29 MONTHS WARMER THAN
NORMAL FROM SEPTEMBER 1920 THROUGH JANUARY 1923. IN TERMS OF SUCH
A LONG STREAK ON THE SAME DEPARTURE SIDE OF NORMAL...THIS WAS THE
LONGEST STREAK OF MONTHS SINCE FEBRUARY 1989-DECEMBER 1989...WHICH
WERE ALL COOLER THAN NORMAL.

ROCKFORD...

AS FOR ROCKFORD...THE TEN MONTHS IN A ROW WARMER THAN NORMAL FROM
OCTOBER 2011 TO JULY 2012 WAS THE LONGEST CONSECUTIVE MONTHLY
STRETCH ABOVE NORMAL SINCE TEN CONSECUTIVE MONTHS ABOVE NORMAL FROM
NOVEMBER 1948 TO AUGUST 1949. THERE WAS AN IMPRESSIVE STRETCH OF 13
MONTHS WARMER THAN NORMAL WAS FROM JANUARY 1938 THROUGH JANUARY
1939. IN TERMS OF SUCH A LONG STREAK ON THE SAME DEPARTURE SIDE OF
NORMAL...THIS WAS THE LONGEST STREAK OF MONTHS SINCE OCTOBER
1978-NOVEMBER 1979...14 CONSECUTIVE MONTHS WHICH WERE ALL COOLER
THAN NORMAL.

IT SHOULD BE NOTED...THAT THE 30-YEAR NORMALS ARE RECALCULATED EVERY
TEN YEARS. THOSE NORMALS...WHICH WERE THE NORMALS AT THE TIME OF
ANY GIVEN YEAR...WERE USED IN THIS DATA. SO FOR EXAMPLE...THE
NORMALS FOR 2012 ARE FROM 1981-2010...WHILE NORMALS IN 2002 WERE
FROM 1971-2000.

$$


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