The new 1981-2010 climate normals are available for Illinois. You can find them through a station list or a Google Map on my homepage.
Climate normals are 30-year averages that are updated every 10 years in the U.S. The National Climatic Data Center produces the climate normals for the US. By settling on a standard averaging period, users are able to compare climate conditions between two or more locations.
By updating every 10 years, the climate normals can reflect data from newer stations as well as reflect any changes to the climate. One impact of switching from the 1971-2000 to the 1981-2010 climate normals was that the cold, snowy winters of the 1970s fell out of the calculations. As a result, the new normal snowfall has dropped a little in most places. For example, the new normal annual snowfall is 3 inches less in Champaign-Urbana.
The National Climate Data Center has a climate normals page dedicated to the new climate normals and frequently asked questions.
Snow Climatology and Extremes for Illinois
The National Climatic Data Center has a web page that generates the snowfall climatology and extremes for any U.S. state except Hawaii (sorry).
Link: http://www.ncdc.noaa.gov/ussc/USSCAppController?action=map
From there you can pick a state and look at state-wide numbers like who had the greatest 1-day snowfall (24 inches at Coatsburg IL on Feb. 28, 1900) or the great snow depth (39 inches at Antioch on Jan. 16, 1979). You can also pull up more detailed station by station analysis of snowfall including averages and dates of the earliest and latest snowfall, etc.
More on Soil Temperatures in Illinois
Here are the average dates in fall when the 4-inch soil temperature falls below 50 degrees (left panel) and below 60 degrees (right panel). Consider these as a “rule of thumb” for planning purposes. Consult the current soil temperatures, as discussed in the earlier post, for decisions on applying nitrogen in the fall.
Central IL tornado climatology updated
The NWS office in Lincoln, IL has updated their tornado climatology for central and southeastern Illinois for the period 1950-2009. During this period McLean County reported an incredible 100 tornadoes, the highest for any county in central Illinois. However, McLean County is the biggest county in this area (a bigger county means a bigger target). This can be partially overcome by calculating a tornado density instead. In that case, Logan County ranks highest in the area with an average of 9.385 tornadoes per 100 square miles. You can click on the individual counties and get more detailed reports of that county, including tracks, dates, magnitudes, deaths, injuries, and property/crop damage of each tornado.
Here is the track map for Champaign County:
