GRAPHICAL
CLIMATOLOGY OF CHICAGO TEMPERATURES, PRECIPITATION, AND SNOWFALL
(1871-PRESENT)
By
Charles Fisk* Latest
Update: 1 July 2009
The following is a graphical climatology of
Chicago, Illinois temperatures, precipitation, and snowfall, from the 1870’s at
the earliest (temperature and precipitation) through 2009. The graphics consist of summary overview
charts followed by year-to-year graphs that depict daily temperature,
precipitation, and snowfall. The daily precipitation observations date from the
start of 1871, temperatures from 10 June 1872, snowfall from the 1885-6 season,
and snow depth from the beginning of 1901.
Data were obtained courtesy of the Chicago
National Weather Service Office, the National Climatic Data Center, and the
Chicago National Weather Service Office’s on-line site:
http://www.weather.gov/climate/index.php?wfo=lot
“Official” observations from 1871 through
June 1905 were taken at a number of sites in the downtown area, those from July
1905 through 1925 at the U. S. Court House. From January 1926 through 20 June
1942 they were made at the University of Chicago. On the latter date the
official site transferred to Midway Airport, and on 16 January 1980 it moved to
O’Hare International Airport, where it remains today (several within-site moves
have been made at O’Hare). The data thus reflect observations made at multiple
sites and exposures (for example, heights of the thermometers above
ground-level) over the years, so interpretations and comparisons should be
taken in this light.
CLIMATE OVERVIEW GRAPHS –
TEMPERATURE:
CHICAGO DAILY TEMPERATURES
(MEAN MAX/MINS & “ALL-TIME” RECORD MAX/MINS)
COMPLETE YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
OTHER DAILY TEMPERATURE
STATS
CHICAGO AVERAGE DAILY TEMPERATURE RANGES, BY CALENDAR DAY
CHICAGO AVERAGE
DAY-TO-DAY VARIABILITY IN MEAN, MAXIMUM, & MINIMUM TEMPERATURE, BY CALENDAR
DAY
CHICAGO SKEWNESS
STATISTICS FOR DAILY MEAN, MAX, & MIN TEMPERATURES, BY CALENDAR DAY
CHICAGO
ANNUAL MEAN TEMPERATURES (1873-2008)
PRECIPITATION:
CHICAGO
YEAR-TO-DATE 2009 PRECIPITATION VERSUS NORMALS AND RECORD WET 2008
CHICAGO AVERAGE
PRECIPITATION, BY CALENDAR MONTH (1871-2008)
CHICAGO RECORD DAILY
PRECIPITATION AMOUNTS
CHICAGO ANNUAL
PRECIPITATION (1871-2008) CHICAGO
ANNUAL PRECIPITATION PROBABILITY PLOT
SNOWFALL:
CHICAGO ONE-HALF, ONE,
TWO, and THREE-INCH SNOW-DAY FREQUENCIES, BY CALENDAR DAY
CHICAGO MEAN, MEDIAN,
AND EXTREME MAXIMUM SNOW DEPTHS, BY CALENDAR DAY
CHICAGO AVERAGE
SNOWFALL, BY CALENDAR MONTH
CHICAGO SEASONAL SNOWFALL
HISTORY (1885-86 THRU 2008-09 SEASONS)
HOURLY CLIMATOLOGY CHARTS :
CHICAGO HOURLY
CLOUD CEILINGS’ CLIMATOLOGY
CHICAGO
MEAN HOURLY TEMPERATURES AND RELATIVE HUMIDITIES
CHICAGO HOURLY
THUNDERSTORM FREQUENCIES
CHICAGO HOURLY MEAN VECTOR
WIND DIRECTIONS AND PERSISTENCIES
CHICAGO
HOURLY PREVAILING WINDS
CHICAGO MEAN HOURLY WIND
SPEEDS
YEAR-TO-YEAR GRAPHS -
The top chart on a given yearly
page (links below) displays “floating-bars” of the daily maxima and minima.
Each bar represents an individual day’s temperature range. Superimposed are two line traces, the upper
one connecting 1872 to present average daily maxima, the lower one 1872 to
present average daily minima. The bars
depict the varying diurnal, synoptic, long-wave, and seasonal influences on
temperature over time, and subjectively, some years’ features can be quite
interesting to look at (see “REPEAT LINKS TO SOME OF THE MORE INTERESTING
YEAR-TO-YEAR GRAPHS, WITH ACCOMPANYING NOTES” section below).
The second
chart down shows the arithmetic departures of day-to-day mean temperatures less
the corresponding 1872-present calendar-day average means. Vertical lines extending upward from the zero
line indicate above average means for the day (colored red), those extending
downward indicate below average daily means (colored blue). In the entire series, greatest positive
departure for any given calendar day is +36 F on 23 January 1909 (associated with
a daily maximum: 65 F, daily minimum: 56 F), the greatest negative departure
-45 F on 24 December 1983
(associated with a daily maximum: -11 F, daily minimum: -25 F).
The third chart down shows the
middle chart’s departures in deseasonalized or
“standardized” form. This adjusts for the fact that individual calendar days
have higher or lower inherent year-to-year variability in mean temperature (and
departures). For example, a daily mean that is 15 degrees below normal in July
is much more anomalous then one that occurs in January. Standardized anomalies are calculated by dividing the arithmetic anomaly by the climatological
mean temperature standard deviation for the calendar day in question, creating
“z-scores”. Through 2006, the most positive z-score was +3.6 for 8 March 2000, the most
negative, –3.6 for 13 February 1905 and 24 December 1983.
The fourth chart down depicts daily
rainfall, the fifth and sixth charts, respectively, daily snowfall and snow
depths.
YEAR-TO-YEAR
GRAPHS - LINKS
1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889
1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909
1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929
1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949
1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
REPEAT LINKS TO SOME OF THE MORE INTERESTING YEAR-TO-YEAR GRAPHS, WITH
ACCOMPANYING NOTES -
1871 – Prelude to Great Fire of
8-10 October, just 3.70” precipitation between 4 July
and 8 October, 35% of average and driest such calendar
period in all history down
to present.
1872 - Minus 23 on 24 December, coldest
December temperature in Chicago until –25 F in 1983 (also on 24th).
1875 - Coldest year in all Chicago history
down to present, also coolest Summer (June-August) and Fall
(September-November).
1877-78 - “Year Without a Winter” –
Warmest winter (December-February) in all Chicago history down to present by
1.5 F, and warmest December-March by nearly 3 F.
1879-80 - Great gyrating warm and cold spells
from late-September through year-end 1879. January 1880 the warmest in Chicago
history down to the present day (by more than 3 F).
1891 - Cool Summer followed by much above
normal September, warmest calendar month of the year. Only
such September in entire Chicago climatic history to be warmest month of the
year.
1892 - Thirteen out of fourteen consecutive days with
measurable rainfall in June. Wettest June (10.58”) in Chicago
history.
1895 -
Long
cold spell over late January to early February.
1896 - Snowiest February in Chicago history (27.8”), but
very forward April and May
1899 - February cold wave drops mercury to –21 F on
9th.
1903-04 - Coldest winter (December-February) in all Chicago
history down to present.
1910 - Warmest March on record on Chicago until 1945.
1911
- Three-day run of 100 F or higher daily maxima
in early July – all time-record for Chicago; but unusual (for mid-Summer) turn
to much cooler than normal later in month.
1913 - Persistent above normal warmth over
November and December.
1915 - Warmest April on record up to this time; but May 2 F
colder than April. Second coolest Summer (June-August)
in all Chicago climatic history.
1918 - 42.5” snow in January, most ever for single
calendar month in Chicago history. Snow depth 25” on 13
January, deepest on record until 1967.
1920-21 - Most snow-free winter in all
Chicago history (9.8” total).
1921 - Warmest year in Chicago history.
1925 - Coldest October in Chicago history.
1926 - Snowiest March on record in Chicago (23.6”), most of
it received near month-end; 10-inch snow depth on 3 April.
1927 - Following a cool Summer,
quasi-periodic much above normal temperature spells in September, October,
& November.
1930 - 90 F on 10-11 April, earliest 90 F daily maxima ever
recorded in Chicago; 75 F on 19 November, warmest ever so late in season.
1931 - Second warmest year in Chicago history, warmest
Fall (September-November).
1931-32 - Following an almost complete
absence of below normal temperatures over November to February, unseasonable
cold sets in during March, coldest month of the ’31-’32 winter season by nearly
3 F.
1934 - 102 F on 31 May; 105 F on 24 July (highest ever
recorded at Chicago ‘official’ station).
1936 - Long cold siege from late January through most of
February. Hot early July - 102 F on 10th.
1938 - 13.6” total snowfall for April (snowiest in
history).
1940 - Snowiest November (14.8”) in Chicago history.
1945 – Warmest March on record in Chicago,
but unseasonably cool from mid-April into early June. Wettest May in Chicago
history (7.59”)
1947 – Wettest April (8.33”) and warmest
August in all Chicago history down to present.
1950 – 67 F on 25 January, highest ever in
calendar month January. Also 84 F on Halloween and 81 F on 1 November, but –1 F
and –2 F on 23-24 November, respectively, earliest subzero readings in Chicago
history.
1951 – Snowiest December (33.3”) in Chicago history down to
present.
1953 – Quasi-periodic much above normal temperature
spells over late-August through mid-November: 101 F on 1-2 September, 99 F on
29 September, 87 F on both 21-22 October, and 71 to 74 F readings over November
15th to 19th, inclusive.
1954 – Eleven-day run of 90 or higher daily maxima in
June. More than 12” rain in October (wettest October in Chicago history.
1955 – Warmest summer (June-August) in all Chicago history
down to present; also warmest calendar month (July: 81.3 F). April
also warmest in Chicago climatic history.
1960 – Coldest March in all Chicago history down to present
by more than 3 ½ F.
1961 – More than 14” rain in September.
1962 – Driest year (22.22”) in Chicago history down to
present.
1963 – Coldest January since 1912, warmest October in all
Chicago history down to present.
1967 - Great 23-inch snowstorm over 26-27 January;
27-inch snow depth in early February.
1974 – 80 F on 3 March, earliest 80 F degree temperature ever
recorded in Chicago.
1976 – 75 F on 27 February, highest ever so early in season
in Chicago.
1976-77
– Great
thermal anomaly “flip-flop” between successive four-month periods:
October-January coldest such period on record, February-May the warmest on
record. January coldest calendar month in Chicago history
(10.1 F).
1977-78
- Snowiest
season in Chicago history up to this time (85.3”).
1978-79 - Heaviest snow season record broken for Chicago (89.7”)
after just one year. Ninety-eight consecutive days with measurable snow cover
(27 Nov to 4 Mar). Record all-time snow depth on 14 Jan (29
inches).
1979 - September driest calendar month in
Chicago history (0.01”).
1982 - Minus 26 on 10 January; Minus 25 on 16 January. Wettest December (8.56”) in Chicago history; 71 F on 2 December.
1983 - Great El Nino year. Wettest
calendar year in Chicago history (49.35”) up to this point. Coldest December, -25 F on 24th.
1985 - Coldest year since 1917. Minus 27 recorded on 20 January – coldest temperature in all
Chicago history down to present. Wettest November (8.22”) in Chicago history.
1986 - 88 F on 29 March, highest ever so early
in season in Chicago.
1987 - August wettest calendar month in Chicago history
(17.10”).
1988 - 104 F on 20 June, 103 F on 25 June, but coldest October
since 1925.
1989 - 6.3” snow in October, cold December.
1992 - 33 F on 27-28 May, 38 F on 21 June –
all coolest so late in season marks. Coolest Summer
(June-August) since 1915.
1993 – Coolest September in Chicago on
record.
1995 - Second warmest summer (76.3 F) on record (to 1955’s
76.4 F); 104 F on 13 July. But 32 F on 22 September, earliest
32 F or lower temperature on record.
1998 - The other great El Nino year of the 20th
century. Warmest year in Chicago since 1931.
1999 - 18.6” snow on 2 January, all-time Chicago heavy
snow record for individual calendar day; 70 F on 11 February.
2000 - Exceptionally mild late February to early
March: 72 F on 25 Feb, 78 F on 6 and 7 March. Second coldest
December in Chicago history.
2005 - Driest calendar year in Chicago (24.09”) since 1962
(22.22”).
2006 - Mildest January in Chicago
since 1933.
2008 - Wettest
calendar year in Chicago history (50.86”).
*Member, American Meteorological Society
mailto:CJFISK@worldnet.att.net
Links
to other sites:
Link to Graphical History of
Minneapolis-St. Paul
Daily Temps, Precip, and Snowfall (1820-Present)
Link to Graphical History of
Downtown Los Angeles Daily Temps and Rainfall (1921-Present)