September 20-26: Record Late Season Heat Facts and Numbers

Public Information Statement...UPDATED
National Weather Service Chicago IL
912 PM CDT Tue Sep 26 2017 /1012 PM EDT Tue Sep 26 2017/

...Record Late Season Heat Numbers...

Late September 2017 has seen near to record warmth across a
sizable portion of the Midwest, including northern Illinois and
northwest Indiana. Following are climatological numbers to put
this late season heat into perspective.

**************************************************************
CHICAGO

Records date back to 1871.

Date   2017 High   Record High   2017 Low  Record Warm Minimum
--------------------------------------------------------------
9/20      92*       91 (1931)       62         73 (1931)
9/21      94*       92 (1970)       72         76 (1931)
9/22      94*       92 (1956)       71         73 (1895)
9/23      95*       91 (1937)       72*        71 (1891)
9/24      93*       91 (1891)       70         71 (1930)
9/25      92*       90 (1933)       67         72 (1920)
9/26      92*       90 (1998)       70         71 (1973)

* = Record

2017 has seen the latest 90+ since 1998 (Sept 26).

Latest 90+ degree reading on record:  Oct 6, 1963 (94)
Latest 95+ degree reading on record:  Sept 29, 1953 (99)

There has not been a heat wave of this duration and magnitude
this late in the season in Chicago on record. Chicago has not 
recorded 7 consecutive days with highs of 92F+ this late in the
year. The previous latest streak of 4+ days in a row of 92F+
was Sept 16-19, 1955. In fact, this year`s streak of 7 days in a
row with highs of 92F+ is only the 2nd time in the past 50 years
that Chicago has seen such a stretch of heat. The other time
was during the heart of summer in the infamously hot and dry summer
of 1988 (July 27-August 4).

Until 2017, there had not been 7 consecutive 90+ days in Chicago
entirely during the month of September. The previous latest streaks
of 7+ days of consecutive 90s were on August 24-September 3, 1953
and August 25-September 3, 1973.

In addition, this is the latest Chicago has ever recorded 3 days
in a row of mid 90s (94F+). The previous record for latest 3+ day
streak of mid 90s was back on Sept 13-15, 1927 and also the same
dates in 1939.

Saturday`s high temperature of 95F tied for the hottest day of
2017. This sets a record for the latest in the year that the
hottest temperature of the year was recorded in Chicago.
Previously, the latest in the year that the annual high
temperature occurred was Sept 14 in 1893, 1915, and 1927.

The daily average temperature on Sept 21 was 83 degrees, which
ties for the warmest daily average temperature on record after
the midpoint of Sept (Sept 21, 1931).


**************************************************************
ROCKFORD

Records date back to 1905.

Date   2017 High   Record High   2017 Low  Record Warm Minimum
--------------------------------------------------------------
9/20      91        92 (1920)       63          74 (1895)
9/21      89        94 (1920)       69          70 (1895)
9/22      92        93 (1937)       67*         65 (1959)
9/23      93*       92 (1937)       66^         66 (1920)
9/24      90        92 (1920)       65          70 (1930)
9/25      92        95 (1920)       64          69 (1972)
9/26      90        92 (1920)       63          69 (1973)

* = Record
^ = Record Tied

2017 has seen the latest 90+ since 2010 (Oct 9).

Latest 90+ degree reading on record:  Oct 9, 2010 (90)
Latest 95+ degree reading on record:  Sept 25, 1920 (95)

Latest stretches of 5+ consecutive days of 90+:
1. September 22-26, 2017
2. September 12-16, 1939
3. September 11-15, 1927

Latest stretches of 4+ consecutive days of 90+:
1. Oct 2-5, 1922
2. Sept 22-26, 2017
3. Sept 12-16, 1939

The latest in the year that the annual high temperature
occurred:  Sept 15, 1927 (99)

The highest temperature in 2017 has been 94 on June 11 and 12.

For more, please see weather.gov/chicago and click on Climate
and Past Weather.

$$

MTF/Izzi/Castro/Rodriguez