Monthly Temperature and Precipitation Departures for 2014 for Illinois

Here are the monthly temperature and precipitation departures for 2014. September joins January, February, March, and July as much cooler than average months. For precipitation, we noted last month that we were regularly alternating between wetter- and drier-than-average months in 2014. That changed in September with two months in a row of wetter-than-average conditions.


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Wet Weather Continues in Illinois, Could Delay Harvest

October is off to a wet start and the wet weather is expected to continue over the next 14 days for Illinois. This could have an impact on the already slow fall harvest season in Illinois. The USDA NASS report on Monday noted that 14% of the corn crop in Illinois was harvested, compared to a 5-year average of 34%. Also, 10% of the soybean crop was harvested compared to the 5-year average of 18%.

Here is the precipitation over the past 24 hours. Amounts of 1 to 3 inches were widespread across central Illinois. This was the same area that received much above average precipitation in September, according to the post on September.


Here is the NWS Quantitative Precipitation Forecast for the next 7 days. The heaviest precipitation is expected to fall in Missouri, Illinois, Indiana, and Michigan. For Illinois, amounts are in the range of 1 to almost 3 inches.  Continue reading

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September Was Cool and Wet for Illinois


September was 1.5 degrees cooler than average and 0.88 inches wetter than average for Illinois. Year to date temperatures were 3.3 degrees below average and the 6th coolest January-September on record. The year to date precipitation was 32.91 inches, 2.5 inches above average.


The statewide average temperature for September in Illinois was 64.4 degrees, 1.5 degrees below the 1981-2010 average.

The statewide average precipitation for September in Illinois was 4.12 inches, 0.88 inches above average. The heaviest rains fell across western and central Illinois with amounts of 6 to 9 inches (map below). A second area of heavy rains occurred south of Interstate 70 near Effingham. The largest monthly total reported so far is Beardstown with 10.72 inches.


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Illinois and Global Temperatures for June-August

Based on the latest updates from the National Climatic Data Center, this summer in Illinois was the 29th coolest. Daytime highs were much cooler than average while the nighttime lows were near-average.

The average maximum temperature in Illinois was 82.3 degrees Fahrenheit, 2.6 degrees below the 1900-2000 base period and the 14th coolest on record.


The average minimum temperature in Illinois was 62.3 degrees F, 0.3 degrees above the 1900-2000 based period.



In contrast to the cool summer in the central US, most of the globe was warmer than average this summer (June-August), according to the National Climatic Data Center. In fact, even in the US, temperatures were significantly warmer in the West than the East.


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When Is Fall? Astronomical, Meteorological, Climatological?


The Quad – University of Illinois in fall color.

No doubt today (September 22) will be announced as the “first day of fall” because of the fall or autumnal equinox. However, that concept refers to the date when we get equal amounts of daylight and dark.  I don’t think it was ever intended that this astronomical event would be the start of fall. In fact, this equinox would be the start of spring in the southern hemisphere. So to be fair to everyone we should call it the September equinox and leave fall out of it.  ;-)

Climatologists and meteorologists prefer to use calendar months to define the four seasons in the US. For example, fall would start September 1 and end on November 30. Not only is this more convenient, because you can use monthly data, but it lines up better with the typical or average temperature pattern for Illinois. Unfortunately, the meteorologists would describe this three-month period as “meteorological fall”. However, I would argue it is “climatological fall” since we are looking at long-term average to determine the season.

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NWS Outlook – Wet October, Warmer Fall for Illinois

There is an increased chance of above-average precipitation for the northern half of Illinois in October and an increased chance of above-average temperatures in October-November-December for all of Illinois, according to the latest outlooks from the NOAA Climate Prediction Center.

October Precipitation

The first map shows the precipitation outlook for October. Wetter-than-average conditions are expected in much of the northern Corn Belt as well. The rest of Illinois is in equal chances (EC) of above, below, and near-average precipitation. All of Illinois has equal chances of above, below, and near-average temperatures. Another way to think of “EC” is that the odds are evenly divided among the three categories.


Click to enlarge.

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Cool, Wet Start to September in Illinois

No surprise – the first half of September was very wet across much of Illinois. And it is raining across central Illinois as I write this.  Temperatures for the first half of September are 3 to 4 degrees below average in Illinois.

The first map show the accumulated precipitation for the Midwest. The largest precipitation totals occurred in western Illinois, southern Iowa, western and northern Missouri, as well as parts of eastern Nebraska and eastern Kansas. A second area of heavy precipitation occurred in northern Wisconsin and northern Michigan. For agriculture, having this much rain at the end of the growing season is probably not welcome.

The second map shows the temperature departures from average across the Midwest. For Illinois, the coolest departures from average occurred in western Illinois – no surprise due to all the rain and cloudiness there. Temperatures were cooler-than-average across the Corn Belt but the departures became increasingly stronger when moving westward and northward.


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