January 15: ORD

Today is January 15th. It's the 15th day of the year. 351 days remain. It's week 3 of the year.

Unless noted, the following data is based upon observations collected by the National Weather Service,Chicago,at O'Hare International Airport (ORD) between November 1978 and last year. Observations have been official at O'Hare since Thursday, January 17, 1980. Before this, the official site was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 31 and the normal low is 16. I've calculated the 33-year averages at 28 and 13.

On the warm side, in 1990 the high was 53 (O'Hare's only 50s high for the date) with a low of 27. A decade earlier, in 1980, the high was 47 with a low of 32. In 2006 the high was 45 with a low of 27. The other warm high was 42 in 2000. The other warm lows were 31 in 2001, 30 in 2002, 30 in 1995, 27 in 1987 and 26 in 2000. The record high of 60 was set in 1949 at Midway. The record warmest low of 40 was set way back in 1894, at a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 33 highs (67%) were in the: 20s (10) and 30s (12). On the warm side, four highs (12%) were in the: 40s (3) and 50s (1). O'Hare didn't have any highs of 40 or higher before 1980 on this date. On the cold side, seven highs (21%) were in the: negative single digits (2) and 10s (a.k.a. teens) (5). O'Hare's coldest high of the date is -9 in 1972.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: In 1978 the high was 18 with a cold low of -1, a cold day. In 1977 the high was 18 with a low of -10, a cold day. In 1976 the high was 37 with a low of 7, a 30 degree spread. In 1974 low was a warm 28 degrees. In 1973 the high was 36 with a warm low of 33, a three degree spread. In 1972 the high was -9 with a low of -17, a very cold day. 1972 was the year of the record coldest high of -5 at Midway. That high of -9 was colder than the record, but O'Hare was not the official station of record for Chicago in 1972. In 1971 the high was a cold 18 with a low of 6, a cold day. In 1965 the high was 21 with a low of 15, a six degree spread. In 1963 the high was 0 with a low of -19, another very cold day. That low of -19 at O'Hare equals the record low of -19 set at Midway Airport in 1979. In 1961 the high was 34 with a warm low of 30, a four degree spread. In 1959 the high was 34 with a cold low of 1, a 33 degree spread.

More recently, we had small spreads of four degrees in 2001 (35/31), four degrees in 2002 (34/30), six degrees in 1995 (36/30) and seven degrees in 1998 (31/24). In 1986 the spread was a large 33 degrees (37/4).

On the cold side, in 1994 the high was -4 with a low of -17. Fifteen years later, in 2009, the high was -1 with a low of -13. Thirty years earlier, in 1979, the high was 11 with a low of -17. Three years later, in 1982, the high was 14 with a low of -9. Another three years later, in 1985, the high was 13 with a low of -4. In 1992 the high was 20 with a low of -10, a 30 degree spread. In 1984 the high was 17 with a low of 0. In 2005 the high was 15 (our most recent 10s high) with a low of 4 (our most recent single digit low). The record low of -19 was set at Midway in 1979. The record coldest high of -5 was set in 1972 at Midway. Other lows in 1979 were -17 at O'Hare, -20 at Barrington and Wheaton, -21 at NIU in DeKalb, -22 west of Crystal Lake at Marengo and -24 at Rockford and Elgin. 18 of the last 33 lows (55%) were in the: 10s (a.k.a. teens) (7) and 20s (11). 11 lows (33%) were in the cold: negative 10s (4), negative single digits (2) and single digits (5). O'Hare's coldest low of the date was -19 in 1963. Other pre-1979 mentionables are -17 in 1972 and -10 in 1977. Four lows (12%) were in the warm 30s. O'Hare's warmest low of the date is 33 in 1973. Through Winter 2010-11, this is the average second coldest day of the year.

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1979 the high was 11 with a low of -17, overall 27 degrees BELOW normal. Then in 1980 the high was 47 with a low of 32, overall 15.5 degrees ABOVE normal. In the second instance, in 2005 the high was 15 with a low of 4, overall 14.5 degrees BELOW normal. Then in 2006 the high was 45 with a low of 27, overall 12 degrees ABOVE normal.

Today is a major day in O'Hare's snow history. In 1979, 1.6 inches fell. This was the fifth day of a 21.7 inch, seven day stretch of snow. This storm changed Chicago politics. The slow response that the city had to cleaning up after the storm was blamed on Mayor Michael Bilandic and his administration. This caused him to lose in the primary election to the eventual new mayor, Jayne Byrne. At O'Hare on the 13th, 15.3 inches fell while at Midway, 16.5 inches fell. This blizzard closed down the city for several days.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:49 and sunrise is at 7:20. Sunset is at 16:46 and twilight ends at 17:17. There's a total of 9 hours, 26 minutes of daylight today and 10 hours, 28 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 6:48 and sunrise is at 7:19. The moon is waning gibbous. Illumination was 63% at midnight, will be 57% at noon and 52% at midnight tonight. Moonset is at 10:28 this morning. Moonrise is at 0:25 tomorrow morning. Moonset is at 11:02 tomorrow morning. Moonlight time is 10 hours, 28 minutes which is 2 hours, 48 minutes shorter than yesterday.

Winter began December 1st and runs for 102 days through March 11th. High temperatures in this period are usually in the 20s and 30s. Highs in the 40s and 50s occur infrequently. Martin Luther King, Jr. Day is tomorrow.