Cool July Across Illinois and the Midwest

Despite the recent short-lived warm spell that ends today, Illinois is on track to be one of the coolest July’s on record. The statewide average temperature from July 1-21, 2014, was 70.4 degrees. That is just 0.1 degrees off from the coolest July on record – set in 2009 with a temperature of 70.3 degrees. Of course we are only two-thirds of the way through the month but the NWS forecast for the rest of July is interesting (shown below).

  1. July 2009: 70.3 degrees
  2. July 2014: 70.4 degrees (as of July 22)
  3. July 1924: 71.1 degrees
  4. July 1967: 71.7 degrees
  5. July 1971: 71.9 degrees
  6. July 1950: 72.0 degrees
  7. July 1915: 72.2 degrees
  8. July 1947: 72.3 degrees
  9. July 1904: 72.4 degrees
  10. July 1905: 72.5 degrees

As this map shows, the cooler-than-average temperatures are not confined to Illinois, but is spread across the Midwest (shades of green show the degree of cooling compared to the 1981-2010 average).


With nine more days to go, the NWS forecasts indicate that temperatures are likely to be below average for the rest of the month. Here are snap shots of the NWS 6-10 and 8-14 day temperature forecasts, as of July 22, showing the large area across the central US expected to have below-average temperatures.  Meanwhile the West Coast will be facing warmer-than-average conditions in a summer shaping up to be hot.

If this forecast holds true, this July could end up in the list of top 10 coolest July’s on record.


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More Cool Weather Ahead?

The NWS Climate Prediction Center released their latest outlook for August and beyond. In the figure below, the top row are the temperature and precipitation outlooks for August. The second row is for August – October. Click to enlarge.

For August, northern Illinois has an increased chance of below-average temperatures, along with Iowa, Wisconsin, Minnesota, and the Dakotas. Precipitation in August has equal chances (EC) of being above, below, or near-average.

For August-October, almost all of Illinois has an increased chance of below-average temperatures. Precipitation during this period has equal chances of being above, below, or near-average.

So far, July is shaping up to be both cooler and wetter than average. Through July 16, the statewide average temperature was 70.9 degrees, 5 degrees below average. Statewide precipitation was 2.9 inches, 54 percent above average.


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Champaign-Urbana Illinois Gets Soaked

Heavy rains fell over Champaign-Urbana, Illinois on Saturday with more rain early Sunday morning. The two-day total through Sunday morning was 4.42 inches at the official NWS COOP station at the Illinois State Water Survey near the corner of First and Windsor in Champaign. Here is the breakdown by day, with the official observation time at 8 am:

  • 0.09 inches of rain by 8 am July 12
  • 4.33 inches of rain by 8 am July 13

The 4.33 inches for July 13, 2014, at the official, long-term site for Champaign-Urbana, falls short of the historical record 1-day total, which is 5.32 inches of rain from August 12, 1993.

Here are the reports from the CoCoRaHS network for Champaign-Urbana, showing two reports of over 5 inches, and several reports of between 4 and 5 inches.


Here is a wider view showing the rains of the last two days from a NWS product that combines radar and rain gage information. The amounts of 2.5 to 4 inches stretches from Chicago down to east-central Illinois with the heaviest amounts of possibly up to 6 inches in Champaign, Piatt, McLean, and Ford counties.


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June in Illinois – Warmer and Wetter Than Average

The statewide average precipitation for June 2014 in Illinois was 6.78 inches, 2.58 inches above average and the 8th wettest June on record. The wettest June on record was 1902 with 8.27 inches. Four out of the last five June’s have been wetter than average in Illinois:

  • 2010: 7.71 inches, 3.51 inches above average
  • 2011: 6.69 inches, 2.49 inches above average
  • 2012: 1.73 inches, 2.47 inches below average
  • 2013: 5.33 inches, 1.13 inches above average
  • 2014: 6.78 inches, 2.58 inches above average 

The statewide average temperature for June 2014 in Illinois was 72.9 degrees, 1.1 degrees above average.

Here are the maps of accumulated rainfall in June, 2014, as well as the departure from the 1981-2010 average. The rainfall was widespread across the state, and above-average as well. The area with the highest departures was the northwest corner of the state. There were 13 stations with 10 or more inches of rain in June. The wettest was Galena with 12.42 inches of rain for the month.

Much of the Corn Belt was wetter than average for June (last map) with precipitation departures from average in the range of 6 to 10 inches. That’s more than double the average in many locations. The results are high flows on many rivers and streams and flooding along the main stem of the Mississippi River south of Dubuque, IA.


Click to enlarge.


Click to enlarge.


Click to enlarge.

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Friday Roundup in Illinois

It is no surprise that June has turned into a wetter-than-average month. The statewide precipitation in Illinois is sitting at 6.1 inches, 1.9 inches above average. Several locations in central and northern Illinois have reported rainfall totals in the 8 to 10 inch range. Two of the highest so far are Dixon (IL-LE-17) with 10.15 inches and Galena (IL-JD-2) with 10.12 inches. We will have the final statistics on June next week.

As the map below shows, areas in green and blue are in the 5 to 12 inch range, and are common across central and northern Illinois, as well as northern Missouri, Iowa, Minnesota, southern Wisconsin, and parts of Indiana.


Of course, lots of rain means lots of runoff and flooding. Most of the rivers and streams in Illinois and the Midwest are having relatively high flows, shown by this USGS map. The green dots show flow in the normal range, blue dots indicate above normal flow, and black dots are record flows for this date.

USGS WaterWatch    Streamflow conditions


Finally, the Chicago area has not only struggled with heavy rainfall events that have caused flooding in June, but they have had an unusually high number of days with fog. Here is the web page from the Chicago NWS office explaining what is going on with this fog.


Click to go to original NWS article on the not so rare summer fog.



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New Climate Outlook for July and Summer – OK for Illinois

Today (June 19) the NOAA Climate Prediction Center has released their latest outlook for July and the rest of the year. One of the factors to come into play this fall and winter is the developing El Niño event in the Pacific Ocean. Unshaded areas show an equal chance (EC) of above, below, or near-average conditions. Click on any map to enlarge.


For July, we have EC for both temperature and precipitation in Illinois, except for a slight risk of below-average precipitation in southern Illinois. We are sandwiched between cooler than average conditions in the north and warmer that average conditions in the south.




For July through September we have EC for both temperature and precipitation in Illinois. From the standpoint of the Corn Belt, the increased chance of cooler than average temperatures in WI, MN, and the Dakotas through September may spell trouble for getting the corn crop to mature in time this fall. Wetter than average conditions are expected in the central West, which could bring some relief to drought conditions in that region.




For December through February, the core winter months, Illinois and much of the northern half of the US has an increased chance of above-average temperatures. This forecast reflects the expectation that El Niño will arrive. El Niño tends to bring milder temperatures in winter for Illinois and wetter conditions in the Southwest and Southeast.


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Looking for Weather Data in Illinois and the Midwest – Try Cli-MATE

The Midwestern Regional Climate Center has extensive databases on daily temperature, precipitation, and snowfall across Illinois and the Midwest. This used to be a subscription-based system. In fact, one of my original jobs at the Illinois State Water Survey was working on the original version of this system, then called MICIS. In 2013 they revamped the system and made it free to everyone. All that’s required is a quick registration. The URL is Check it out!

I use it for almost all my data, mapping, and plotting needs at work. For example, here is a plot for Chicago of daily temperature and precipitation so far in June of this year. This is a screen shot, the live version allows the pop-up window to move with the cursor.



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