Chicago's largest day-to-next temperature changes
In the period Nov. 1, 1870, through Jan. 30, 2008
temperature rises
58º from 0º to 58º February 13-14, 1887
58º from 15º to 73º March 10-11, 1972
57º from 24º to 81º March 31-April 1, 2003
temperature falls
61º from 74º to 13º November 11-12, 1911
58º from 62º to 4º February 8-9, 1900
58º from 49º to -9º December 13-14, 1901
Arctic air: A type of air mass whose characteristics are developed in the cold season over ice- and snow-covered areas of the far north. It has low temperatures, low moisture content, and is very stable. Air masses of arctic origin cover Chicago about six percent of the time.
Arctic outbreak: The rapid movement of a mass of air originating above the Arctic Circle southward to the Gulf of Mexico, or farther. Arctic outbreaks bring Chicago its lowest autumn and winter temperatures; also called "polar outbreak."
Cold wave: In popular usage, a period of very cold weather. Meteorologically, a rapid fall in temperature within 24 hours to temperatures requiring substantially increased protection to agriculture, industry, commerce and social activities.
Norther: In popular usage in the southern United States, especially Texas, a strong cold wind from the northwest, north or northeast. It is the cold outbreak associated with the southward movement of a frigid air mass.
Blue norther: In popular usage in the Southern Great Plains, a blast of bitterly cold arctic air that surges south across Texas during the winter, bringing strong north winds and a sudden, sharp temperature drop.
Chicago snow facts
(based on 123 years of snow statistics beginning with the winter of 1884-85)
8.2 inches
On average, that is the largest snowstorm that Chicago can expect in any given winter season.
In Chicago, the winter's biggest snowstorm has ranged from a puny 2.4 inches during the 1921-22 snow season to 23.0 inches in 1966-67.
Cryosphere: The portions of the Earth (in the atmosphere, at the surface, in the ground) in which water is in solid form. It includes snow and ice crystals in the air, snow cover and ice caps, floating ice (on rivers, lakes, oceans), glaciers, permafrost, etc. The word is derived from the Greek "kyros," meaning frost or icy cold.
Intergelisol: A sub-surface layer of frozen ground that might persist for a few years but is not permanently frozen ground and is not considered to be permafrost (soil and rock whose temperature is permanently at or below 32 degrees).
Mollisol: In regions of permanently frozen underlying soil, mollisol is the surface layer that freezes in the winter and thaws in the summer. It varies in thickness from a few inches to several feet.
Pereletok: A sub-surface layer of frozen ground that might persist for a few years, but is not permanently frozen and is not considered to be permafrost. The term is Russian, meaning "survives over the summer."
Permafrost: Permanently frozen ground; it underlies about 85 percent of the state of Alaska, and in northern Alaska it reaches its greatest thickness, about 2,000 feet.
Subgelisol: Unfrozen ground beneath permafrost.
Talik: Permanently unfrozen ground in regions of permafrost.
Icebox of the nation
Communities claiming to be the “nation’s icebox” include Pellston, Mich., International Falls, Minn., Fraser, Colo., Truckee, Calif., Stanley, Idaho, and West Yellowstone, Mont. Here are their average annual temperatures. You be the judge.
34.8º Fraser, Colorado
35.4º Stanley, Idaho
36.5º International Falls, Minnesota
40.2º West Yellowstone, Montana
42.7º Pellston, Michigan
44.4º Truckee, California
-20ºF
At Chicago, temperature readings that cold (or colder) are exceedingly rare occurrences. So rare, in fact, that they have appeared only 15 times since the inception of Chicago's official temperature records on November 1, 1870.
If you experienced any of them, chances are you have a vivid memory of the event.
Here they are, listed in chronological order:
1 -21º Sunday, Dec. 22, 1872
2 -23º Tuesday, Dec. 24, 1872
3 -20º Saturday, Jan. 9, 1875
4 -20º Monday, Jan. 25, 1897
5 -21º Thursday, Feb. 9, 1899
6 -26º Sunday, Jan. 10, 1982
7 -25º Saturday, Jan. 16, 1982
8 -23º Sunday, Jan. 17, 1982
9 -21º Friday, Dec, 23, 1983
10 -25º Saturday, Dec. 24, 1983
11 -20º Friday, Jan. 20, 1984
12 -22º Saturday, Jan 21, 1984
13 -23º Saturday, Jan. 19, 1985
14 -27º Sunday, Jan. 20, 1985
15 -21º Tuesday, Jan. 18, 1994
Wind chill temperature: The temperature of still air that would remove heat from an exposed human body as quickly as it is being removed by the existing combination of actual air temperature and wind speed. Humidity and evaporative cooling are not taken into consideration.
Apparent temperature: The heat index; using air temperature and relative humidity, how hot it feels to an "average" person (147 pounds) wearing light clothing and walking 3.1 m.p.h. in a wind that is blowing 5 m.p.h.
Temperature: A measure of the internal energy that a substance contains. The degree of hotness or coldness of a substance, or of the environment. Air temperature is the most frequently measured atmospheric variable.
