Average Date of First Snow in Illinois

I have noticed that the average date of the first snow is a popular search term on the blog, so here is the reposting of the median dates of the first measurable snowfall of the season in Illinois. This map is based on 1971-2000 data. While it is not based on the current 1981-2010 averages, the map is still relevant for the purpose of getting an idea of the dates. Measurable snowfall means at least a tenth of an inch.

Median Date:

In the northern third of Illinois, the first snowfall occurred around Thanksgiving. The dates switch from November to December once you reach central Illinois (just north of a line between Quincy and Champaign). By the time you reach Carbondale, the date can be as late as December 20. From this you can see that we are by no means behind schedule this year.

date of first snow

Early Date:

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Illinois – Coolest Place to Live in 2014?

Illinois was one of the coolest places to live in 2014, at least in terms of temperature, according to the recent annual report released by the National Centers for Environmental Information (NCEI). In the map below, the areas in blue show areas where the temperatures were much colder than average for the central US and eastern Canada, while the West and Alaska were much warmer than average (areas in red).

Click to enlarge.
Temperature departures from the 1981-2010 average. Blue means colder than average while red means warmer than average. Click to enlarge.

According to the latest figures, the average temperature for Illinois in 2014 was 49.5 degrees, 2.7 degrees below the 1981-2010 average, and the 6th coolest year on record for Illinois.

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Historical Tornadoes in Illinois and the US

While tornadoes can happen any time of the year, the tornado season really starts to ramp up in March in Illinois (see plot below) and remains active through the spring and on into summer. April, May, and June are the three standout months historically. So far 2015 has been very quiet with no severe weather reported in Illinois so far, according to NOAA.

tornado-month

You can see more plots like this on our tornado plots page.

Historical Tornado Tracks

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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.

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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.

Chance of a White Christmas

I just heard Bing Crosby on the radio and it reminded me that it’s time to do the annual post on …

What are the historical chances of a White Christmas (defined as at least an inch of snow on the ground on Christmas Day)? The first map below the shows the odds across the state. It should come as no surprise that the highest odds are in northern Illinois.  In general, the odds are about 40-60 percent in the northern third of Illinois, 20-40 percent in central Illinois, and 0-20 percent in southern Illinois.

There can be large differences between nearby sites. Snowfall is notoriously difficult to measure with the potential for two nearby sites having different results due to exposure to the sun and the wind.

WC_Chance_8110

After a cold November, December has been much milder this year. The latest NWS 8-14 day forecast includes December 25 and continues to show Illinois with a good chance of warmer-than-average temperatures. And today there is not much snow in Illinois (map below). Stay tuned to your local forecast as we get closer.   Continue reading

October Cooler and Wetter Than Average So Far in Illinois

The statewide average temperature for October so far in Illinois is 56.5 degrees, 1.4 degrees below average. The statewide average precipitation for October so far is 2.5 inches.

Here is the map showing how the precipitation has fallen in Illinois and surrounding states. The heaviest amounts in Illinois were the 3 to 5 inches between Interstates 70 and 74. Amounts of 1 to 3 inches were common in the northern and southern thirds of the state. The largest total so far is 8.38 inches reported at Greenfield in Greene County

Most of Missouri has seen amounts of 3 to 6 inches or more as well as parts of Indiana and Michigan. It was a little drier in the Minnesota, Wisconsin, Iowa, Ohio and the rest of Indiana where amounts of 0.5 to 2 inches were common.
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