Weather data--get it here free!

Weather data--get it here free!

Be thankful we're not getting all the government we're paying for.  Will Rogers


Almost everybody sees weather as a safe subject of conversation. But for farmers, weather is business. Why might pork producers want to know about historical weather and probabilities of fall weather events?  How about barn management, manure spreading, and winter emergency planning, for starters?


Forecasts and weather history bookmarks—ready, set, click! Most people who use computers and smart phones have favorite sites for quick weather information.  For forecasts, I usually pick the government one: NOAA, the National Oceanic and Atmospheric Administration.  The CAFO permit section in Part 502 of the IEPA regulations also references a couple of NOAA sites.  These give precipitation and temperature forecasts that are required for 502.620, “Protocols to Land Apply Livestock Waste,” and 502.630, “Protocols to Land Apply Livestock Waste During Winter.”  Recall that operators of Unpermitted Large CAFOs who want to maintain the Ag Stormwater Exemption also must use the weather forecast information sources that are listed for CAFO permit holders, if those operators need to spread manure on frozen or snow-covered ground.  The NOAA sites are managed by National Weather Service’s Meteorological Development Laboratory, Statistical Modeling Branch, Silver Spring, MD, and there are two URL’s.  The MAV site uses graphics and seems more straightforward to me:

The “bullform” site at is in table form, and might take some more study to interpret.  My pick is the former one, since I like colored maps.  At either site, try not to get bogged down by all the acronyms, as the government-speak can be a real turn-off. 


For precipitation forecasts at the MAV site, pick from the “precipitation” menu on the left.  You have two types of choices, the precipitation quantity total, and the precipitation thresholds.  To conform to the 502 regulation, pick the threshold maps such as the 24-hr, 0.10 inches or more (winter) and 24-hour, 0.25 inches or more (not winter); look at the top of the map for the probability colors legend.


For winter maximum daytime temperatures, which determine the “spreading window” open for surface application on snow- or ice-covered ground because of the daytime melting conditions prohibition, at the NOAA forecast graphics site you must use the GFSX/MEX MOS option, because that is the only one that projects temperatures over the next seven days.  The other options (GFS MOS – CONUS and NAM/MET MOS) only go out two days.  I recommend you explore this site before you need it, make some notes, and bookmark it in your browser.


When I need Illinois climate history, my favorite is the Illinois State Water Survey at Champaign, which has a website that links to all sorts of weather facts.  To be frank, the trouble with the ISWS website is that there is so much to see, you can get lost.  Before getting to the really fun stuff, there is one more precipitation forecast item that is required in the CAFO regulation Part 502.630 (a), “Winter Application Prohibition”; it applies only to those CAFOs that have manure storages that are exposed to direct precipitation, such as lagoons and outdoor tanks.   For the winter manure management plan, those outside storages must predict their additional capacity for the average monthly precipitation and runoff during the months of December through March.  Illinois has a quick-and-easy table for many sites around the state, and you can find those at Click on the name of the station nearest your facility, and read the row under “Precipitation-Related Normals.”  Then add up the amounts for those four winter months.  Don’t forget to add in the 25-year, 24-hour storm event for existing swine Large CAFOs, and something larger (I’d suggest 100-year, 24-hour) for new large swine CAFOs.  For most of Illinois, the 25-year, 24-hour storm event is about 5.5 inches of rainfall, with 6 inches being the highest, in Pope County; the 100-year, 24-hour storm event is about 8” for all but some very small areas of the state.  A heavy-rainfall frequency atlas publication for Illinois, using data from 1901-1983, can be found at These records are getting some age on them, so use with caution, but they are still viewed as “official.”


There are quite a few breeding facilities around the region that use both evaporative cooling and air filter systems.  Managers need to know when to schedule cooling system maintenance and major barn ventilation adjustments, such as switching to cool-season air filtration.  Historical data for your locality can help make those decisions.  For example, let’s say I have a facility near Fairfield and I’d like to know if September is a good month to shut down the evaporative cooling system for the season, or if there are still lots of heat stress days ahead when I really need to run the cool cells.  I could quickly find the maximum daily temperatures and average dew point temperatures for each September at the Fairfield station, for all the years from 1998 to the present at the archives  To see data tables from year to year at this site takes just a couple of mouse clicks.  Granted, predicting Illinois weather is an art form, but you can certainly improve your odds by having longer term historical data at your computer; it sure beats relying on memory.


Soil temperature is a major factor in nitrification of manure ammonium-nitrogen, and in other soil processes, according to agronomists.  Farmers are being urged by university crop sciences departments, NRCS, EPA, and various water-quality stakeholders to avoid fall-applying nitrogen fertilizers until soil temperatures drop to 50F or below (see the Illinois Nutrient Loss Reduction Strategy at if you haven’t kept up).  The “soil as nitrogen refrigerator” concept applies to manure as well as to commercial N.  So can we point to historical fall soil temperatures data as a basis for scheduling manure application?  You can certainly locate this week’s soil temperatures around the state, using and just pick your closest station.  You can also find historical data in nice graphical form, starting at the same page, where you pick your station, then click on “Soil temp 4-inch” at the bottom of the page, under the Statistics group.  You’ll see the median average, maximum, and minimum soil temperature curves for twelve months, compiled over multiple years.   At the Freeport station, for example, the median (i.e. half the years are above, half below) maximum soil temperature dropped below 50F by November 1.  Maybe this sort of data can also help you decide whether to use a nitrification inhibitor for fall-applied manure in warm soils.


There are some other near-term data at the site you might like, such as wind speeds and directions.  These are good data to record when you are surface-applying manure in the neighborhood, to document efforts you made to keep odor from drifting toward residences. Nineteen stations around the state give enough resolution for many types of data.  Pick a station from the map, and get a quick snapshot of yesterday’s averages from that spot in the state. (Data are archived, if you need to catch up some old records.)

Precipitation totals are more variable, so you need to keep your own rain gauge.  Minimum and maximum air temperatures, soil temperatures, wind speeds and directions, and solar radiation, should be good-enough-quality data for your location, using the nearest of the nineteen weather stations.


 Here’s another nugget.  Illinois State Climatologist data—117 stations around the state, with data from 1901 to 2015 (  You can quickly select a station and get monthly and seasonal precipitation, temperatures, snow days, etc.  There are “wind roses” available for the major airports around the state.  The wind rose data, in combination with local maps of the neighborhood, can be useful for siting facilities in relation to homes, such that odor nuisance complaints may be minimized.


Leave the weather forecasting to the experts, but you can learn a lot about Illinois conditions by looking at historical records.  Furthermore, those records are a click away, as the saying goes.  I recommend having a peek at them, and making bookmarks.  I think you will go back to these sites again and again.  If nothing else, you can always have real data to spar with the old-timers when they start with “I remember the winter of ’77….”