Category: Fall

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Fall Color in Illinois

I love all four seasons in Illinois but I especially like fall. In fact, you could say I’m a falloholic. What’s not to like – the air is cool and crisp and the cloud formations are spectacular. One of the best things about fall is the changing color in the trees, shrubs, and grass.

Henry Garnet’s Sweetspire in the author’s front yard.

A great website for all things related to fall color is the University of Illinois Extension site called “The Miracle of Fall“. Check it out for fall color, foliage updates, photos, festivals, etc. You can also find out about fall activities in Illinois at the Office of Tourism site “EnjoyIllinois.com“. A few other sites to explore are:

One of things I get asked every year at this time is, “what is the effect of weather on this year’s fall color?” It’s hard to answer because there is no formula for this. In general, you don’t want drought conditions because the leaves just turn brown and fall off. Instead, you want nights to be cool but not freezing to trigger the change in leaves. Also, you want mild day time temperatures (not too hot) and sunny weather to really make the colors pop.
I hope you take time to enjoy fall in Illinois. I know I will.

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Record High Sunshine in October

The Illinois State Water Survey has this fascinating press release.
October Solar Radiation in Illinois: Record High in 2010, Record Low Last Year
11/9/10
Source: Bob Scott, 217-333-4966, rwscott1@illinois.edu
Did it seem to you that the weather in October was quite a bit sunnier than in Octobers of the past? Do you remember last October as being rather cloudy?
If these are your impressions, you are correct, according to Bob Scott, Director of the Water and Atmospheric Resources Monitoring Program at the Illinois State Water Survey, a division of the Institute of Natural Resource Sustainability. Scott operates an array of weather sites across the state called the Illinois Climate Network, and one of the sensors on the stations measures solar radiation.
Solar radiation totals for October 2010 were higher than in any past October since sites were installed in 1989, while the solar radiation totals for 2009 were the lowest.
“Our sensors measure what we call direct solar radiation,” Scott said. “This includes pure sunshine and reflected sunshine from clouds and blue sky.”
October typically is drier than the spring and summer months that precede it, and sunshine in October is in a seasonal decline with fewer daylight hours and the sun getting progressively lower in the sky.
“But this October was much drier than normal,” Scott said. “Consequently, there were many more days with bright sunshine and fewer days with clouds and rain, as opposed to last October which had many rain events.”
During the 20-year history of the weather station in Champaign prior to last year, sunshine in October has averaged about 379 mega joules per square meter.
If you ignore the units, Scott said, the range of solar radiation values in October in Champaign through 2008 varied from a low of 328 in 2004 to a high of 414 in 1992. The very wet October of 2009 had a total of 264 units of solar radiation, while the very dry October of 2010 reported 449.
“Both prior maximum and minimum values were slammed in the past two years,” Scott reported.
The current dry conditions have now continued into November with strong indications that it too will see above normal solar radiation.
As far as a cause for these events, “There is none,” said Scott. “Our data by themselves are far too short of a record to suggest a cause, and they are on opposite sides of the scale from each other. Without more information, these data must be categorized right now as simple natural variability.”
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October Was Warm and Dry in Illinois

Precipitation

For Illinois, the statewide average rainfall for October was 1.4 inches, 1.5 inches below normal or 48 percent of normal. This ranks as the 20th driest October on record. The largest monthly rainfall total was reported at Belvidere with 3.94 inches. See map below for rainfall departures across the state.
While northern Illinois was close to normal on rainfall in October, parts of southern and eastern Illinois remained dry. The U.S. Drought Monitor lists those areas as “abnormally dry” and southeastern Illinois as”moderate drought”. At this time of year, the main impacts on agriculture would be on pasture conditions and winter wheat.

Soil Moisture

With the vegetation preparing for a long winter’s nap and lower temperatures, the demands on soil moisture are close to zero. So soil moisture should start to recover in the next few months even if precipitation remains below normal. The Illinois State Water Survey posts their latest soil moisture survey a few days after the end of the month here.

Temperature

The statewide average temperature for October was 56.2 degrees, 1.6 degrees above normal. The highest temperature for the month was reported at Fairfield with 93 degrees on October 10. The lowest temperature for the month was reported at Minonk with 22 degrees on October 29 and Sidell with 22 degrees on October 30.

Frost

During October, nearly all of Illinois has experienced temperatures down to 32 degrees and many areas have reached 28 degrees or less. See map below.

Figures

 

October rainfall Illinois
October rainfall departures from normal.

freeze Illinois
Occurrence of Frost (32F) and Freeze (28F) in Illinois at end of October 2010.

 
 
All data are preliminary.