Last Below Zero Weather of the Season? I Hope.

Here are the lows this morning, courtesy of the National Weather Service office in Lincoln. Areas in blue were below zero. Champaign-Urbana reached -9 degrees, breaking the old record of 4 degrees set in 1899.


Of course, widespread snow cover (map below), clear skies, and calm winds were contributing factors in the hopefully last round of below-zero weather this season. nsm_depth_2015030605_Midwest



    DANVILLE AIRPORT                      -10
    ELIZABETH                             -10
    FREEPORT                              -10
    MCHENRY                               -10
    ROCHELLE AIRPORT                      -10
    DECATUR AIRPORT                        -9
    SIDELL 5NW                             -9
    STERLING AIRPORT                       -9
    PAW PAW 2NW                            -7
    WATSEKA                                -7
    MATTOON AIRPORT                        -6
    OGDEN                                  -6
    PANA SEWAGE PLANT                      -6
    PAXTON 2WSW                            -6
    ALTONA                                 -5
    AURORA AIRPORT                         -5
    DIXON                                  -5
    DWIGHT                                 -5
    LINCOLN NWS                            -5
    NEOGA 4NW                              -5
    ROBINSON WTYE                          -5
    ROCHELLE                               -5
    ROCKFORD AIRPORT                       -5
    ROSICLARE                              -5
    WAUKEGAN AIRPORT                       -5
    BARRINGTON 3SW                         -4
    EFFINGHAM 3SW                          -4
    KEWANEE                                -4
    PARIS SEWAGE PLANT                     -4
    RAMSEY                                 -4
    SULLIVAN 3S                            -4
    MONMOUTH                               -3
    MUNDELEIN 4WSW                         -3
    TUSCOLA                                -3
    BROOKPORT DAM                          -2
    CARBONDALE AIRPORT                     -2
    CHICAGO DUPAGE AIRPORT                 -2
    COAL CITY 4NNW                         -2
    KANKAKEE                               -2
    LACON AIRPORT                          -2
    PRAIRIE CITY 2S                        -2
    GRAND CHAIN DAM                        -1
    MINONK                                 -1
    MORRIS                                 -1
    MT VERNON                              -1
    OLNEY 2S                               -1
    BLOOMINGTON 5W                          0
    CHICAGO OHARE AIRPORT                   0
    GALESBURG                               0
    MOLINE AIRPORT                          0
    OTTAWA 5SW                              0
    SMITHLAND LOCK AND DAM                  0
    WINDSOR SEWAGE PLANT                    0
    ELGIN                                   1
    JOLIET LOCK AND DAM                     1
    MACOMB AIRPORT                          1
    PERRY                                   1
    SPRINGFIELD NE                          1
    AURORA                                  2
    CASEY                                   2
    CHICAGO BOTANIC GARDENS                 2
    GLADSTONE LOCK AND DAM 18               2
    JACKSONVILLE                            2
    NEW BOSTON LOCK AND DAM 17              2
    NORMAL 4NE                              2
    PARK FOREST                             2
    WINCHESTER                              2
    GRIGGSVILLE                             3
    RUSHVILLE 4NE                           3
    WHEATON                                 3
    CHICAGO WHEELING AIRPORT                4
    JERSEYVILLE 2SW                         4
    PITTSFIELD                              5
    BENTLEY                                 6
    CHICAGO MIDWAY AIRPORT                  6
    NASHVILLE                               7
    QUINCY AIRPORT                          7
    QUINCY LOCK AND DAM 21                  8
    KASKASKIA LOCKS                        10
    CAHOKIA AIRPORT                        14
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A Weak El Nino Has Arrived, Another Winter Storm for Southern Illinois


El Niño Arrives in 2015. This image shows the average sea surface temperature for February 2015 as measured by NOAA satellites. The large area of red (warmer than average) can be seen extending through the equatorial Pacific. (Credit: NOAA)

Today the National Weather Service reported that the long-awaited El Niño has arrived in the Pacific Ocean. El Niño occurs when we have above-average temperatures in the Pacific Ocean along the equator. It alters the Pacific weather pattern, which in turn alters our weather patterns over the US. The NWS forecasters say “it is likely (50 to 60 percent chance) that El Niño conditions will continue through summer. ” Due to the weak nature of this event, they are not expecting widespread or strong impacts from this event.

In other news, far southern Illinois was hit this week with another winter storm that passed through Arkansas; southeastern Missouri;  southern Illinois, Indiana, and Ohio; as well as most of Kentucky and points beyond. Some of the largest snowfall totals from this event include Grand Chain Dam with 10.0 inches and Brookport Dam with 9.0 inches.


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Winter Finishes Cold and Snowy in Illinois

The statewide average temperature for the three winter months of December, January, and February in Illinois was 26.1 degrees, 7.5 degrees below average. While cold, it was not nearly as cold as last winter’s 21.7 degrees. This winter ranks as the 30th coldest on record.

winterThis winter started off mild with an average December temperature of 33.9 degrees, 4 degrees above average.  The average temperature in January was 25.7 degrees, only 0.7 degrees below average, and the average in February was 18.6 degrees, 12.3 degrees below average. See figure to the left, click to enlarge. Last winter, all three months were well below average.


Snowfall was above average for the winter from December through February. Most of that fell in February. December was snow-free for most of the state except in the far west. Snowfall was common in January but below average except for a band across northern Illinois. Major snows occurred in February to bring up the winter snowfall totals across the state. Above-average snowfall occurred across northern and western Illinois as well as far southern Illinois. The maps below show the observed amounts and departure from average.



map1The average precipitation for December-February was 4.97 inches, 1.85 inches below average. In fact, most of the Midwest received below-average precipitation this winter (figure left). Precipitation is a measure of both rainfall and the water content of any snow. While we received above-average snowfall, the water content of that snow was not always great. In a typical year we can get rain in winter, but not so much this winter. This kind of precipitation deficit would be a concern during the growing season. However, in winter the water demand is low.

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February – 7th Coldest on Record for Illinois

The statewide average temperature for February was 18.6 degrees. That is 12.3 degrees below the 1981-2010 average and the 7th coldest February on record. By comparison, February 2014 was 9th coldest at 19.5 degrees.

Here are some amazing statistics for Chicago. February was tied with 1875 for the coldest on record, according to the Chicago National Weather Service.  The average temperature for February was 14.6 degrees, 13.1 degrees below average. In addition, it was the 10th coldest month overall on record. February snowfall in Chicago was the third largest on record with 26.8 inches, 17.7 inches above average.

Snowfall for February in Illinois was widespread and well above average. Amounts of 15 to 20 inches were common in western and northern Illinois and 10 to 15 across central Illinois and parts of far southern Illinois. This was 8 to 12 inches above average in many locations. See maps below. Click to enlarge.

Some other February snowfall totals from around the state:

  • Chicago Midway AP: 28.3 inches
  • Rockford: 14.7 inches
  • Peoria: 12.8 inches
  • Quincy Lock and Dam: 11.2 inches
  • Springfield: 22.6 inches
  • Champaign-Urbana: 12.4 inches
  • Bloomington-Normal: 13.0 inches
  • Carbondale: 6.0 inches

The statewide average precipitation (rain plus the water content of snow) for February was 1.5 inches, 0.5 inches below average. Most of the state received 1 to 2 inches of precipitation, except for far southern Illinois which got 2 to 3 inches. See the second batch of maps for precipitation and precipitation departures from average.

Continue reading

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February – East Freezes While West Warms


This map was created by the PRISM climate group out of Oregon State University. You can visit their homepage at

While Illinois and the eastern half of the US freezes, temperatures in California and the West are well above average this month. Here is the map of temperature departures from average for the first 25 days of February. This pattern of extremes was the theme of 2014, diminished in December and January, only to return in February 2015. The temperature pattern is a result of a persistent ridge of high pressure in the West and a trough of low pressure in the East. This is discussed in some detail over at

Goldilocks’ Porridge: there is a tiny white strip on the map from Montana, through the Plains states, and into Texas, where temperatures are within a degree of average – not too hot, not too cold, but just right.

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February On Track To Be Among The Coldest on Record for Illinois

image004February 2015 is on track to being one of the coldest February’s on record for Illinois. Data through February 24 puts the statewide average at 19.4° F. This is 11.5°F below average and slightly colder than last February’s 19.4°F. Before February, this was shaping up to be a mild winter with near to above-average temperatures (see graph to the left, click to enlarge).

At this point, February 2015 is ranked as the 8th coldest on record, edging out 2014 (see table below). The NWS forecasts show that temperatures for the rest of February will be 15 to 20 degrees below average. Therefore it is possible that it could move up the ranks. I will post more on this at the end of the month.

Ten Coldest February’s in  Illinois

  1. 1978 (16.9°)
  2. 1936 (17.2°)
  3. 1979 (17.4°)
  4. 1905 (17.6°)
  5. 1895 (17.7°)
  6. 1899 (18.0°)
  7. 1902 (19.2°)
  8. 2015 (19.4°) ** as of February 24
  9. 2014 (19.5°)
  10. 1914 (20.6°)

Statewide records go back to 1895.

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Will Spring Ever Get Here? Yes It Will.

With snow this weekend and another round of cold temperatures expected in coming weeks, it feels like spring will never get to Illinois. But it will arrive someday – I promise.

Earth's orientation to the sun on the equinox.

Earth’s orientation to the sun on the equinox. Click to enlarge.

In coming weeks, many will point to the spring equinox as the start of spring, which is March 20 this year. The equinox is an astronomical event when the Earth’s axis is at a 90 degree angle to the sun (see figure). In theory, the length of day and night are the same around the world. However, due to how we calculate sunrise and sunset, and how the earth is not a perfect sphere means that the days and nights are not exactly equal in length on the equinox. However, that’s a story for another day.

The bigger problem with the equinox definition is that the spring and fall equinox*, as well as the winter and summer solstice, do not line up well with the annual march of temperature (see figure below for Chicago). With spring, temperatures on average are already warming significantly by March 21, compared to temperatures in January and February. By the arrival of the summer solstice, temperatures are already getting very close to their annual maximum.

image013As a result, many climatologists and meteorologists use calendar month definitions that line up better with the average annual changes in temperature. It works best for summer (June-August) and winter (December-February) in capturing the warmest and coldest periods of the year. In spring (March-May) and fall (September-November), it works well at capturing the strong transition in average temperatures. Several professional have called the period March-May “meteorological spring”, but it is based on climatological data so the better term is “climatological spring”.

Of course, all of this is a bit academic. We all carry our own definition of spring that is probably more in line with nature – the first signs of green grass, the buds swelling on trees and shrubs, increased activity in wildlife (especially birds). I think the one thing winter does best is to make us appreciate spring even more.

*the use of words like winter, spring, summer, and fall, are in reference to the Northern Hemisphere.

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