July 2012 Climate Summary: One of the Warmer and Drier July Months on Record

 

 Departure from normal of July temperatures.  Image courtesy of Midwestern Regional Climate Center.

Percentage of July rainfall versus normal.  Image courtesy of Midwestern Regional Climate Center.

Average temperature vs normal
(click image to enlarge)

Observed rainfall vs normal
(click image to enlarge)

July of 2012 will go down as one of the warmest and driest on record for many areas of central and southeast Illinois.

The first several days of the month were very hot, with highs frequently above 100 degrees, including temperatures of 105 degrees from the 6-8th in many areas.  The brutal temperatures eased a bit, but largely remained in the 90s through the middle of the month, before 100+ degree readings began returning on the 18th.  The month closed with highs in the upper 90s to around 103 degrees.   The number of 90-degree days during July broke records in several instances (see table below).  The only positive aspect to the heat was that humidity values were well below what would normally be seen in July, so heat index readings were frequently near or only a couple degrees above the actual temperature.  Statewide, it was the 2nd hottest July on record, with an average temperature of 81.8 degrees (surpassed only by July 1936).


Location

Record Days

2012 Days

Average Days

Records Began

Charleston

28 (1936)

30

12

1896

Danville

28 (1921)

27

12

1895

Decatur

  28 (1921+)

21

13

1894

Effingham

27 (1954)

29

13

1951

Galesburg

26 (1901)

19

8

1897

Jacksonville

29 (1916)

26

13

1895

Lincoln

30 (1916)

21

12

1906

Normal

   27 (1916+)

23

12

1893

Olney

29 (1901)

28

15

1897

Palestine

30 (1921)

26

15

1892

Paris

30 (1921)

26

12

1893

Peoria

   26 (1901+)

26

11

1883

Springfield

27 (1901)

28

11

1879

Urbana

25 (1921)

26

9

1889

Rainfall was very far below normal, typically below an inch in most areas.  Rainfall over much of central and southeast Illinois was about a tenth to quarter of what would normally occur in July. Some of the driest locations included Paris, which measured only 0.02 inch of rain (2nd driest July on record), Charleston (0.08 inch, driest July on record), and Havana (0.20 inch, driest July on record).  Isolated storms did produce rainfall over an inch at times, but this occurred on such a small scale that areas only a couple miles away frequently missed out on the heavier rains.  Statewide, it was the 4th driest July on record (average rainfall of 1.47 inches).

Between the intense heat and the lack of rainfall, drought conditions rapidly worsened over the area.  By the end of the month, nearly all of central and southeast Illinois was considered to be in extreme drought.   Burn bans became common across the area, and several locations began to implement mandatory or voluntary water conservation measures.

Here are preliminary monthly climate summaries for area cities.  Please note that in the following list, only Peoria, Lincoln, and Springfield are considered "official".  Other stations listed are "supplementary", and are not considered the official observing site for their respective locations.  (Data for other official observing sites is available at http://www.nws.noaa.gov/climate/xmacis.php?wfo=ilx ).



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