February 11: ORD

Today is February 11th. It's the 42nd day of the year. 324 days remain. It's week 6 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 34 and the normal low is 19. I've calculated the 33-year averages at 32 and 15.

On the warm side, in 1999 the high was the record high of 70 with a low of 28, a 42 degree spread. That high of 70 is the earliest 70s high of the year in Chicago record-keeping. A decade later (and three years ago), in 2009, the high was 50 with a low of 36. In 1998 the high was 45 with a low of 37 (O'Hare's warmest low of the date). In 1984 the high was 45 with a low of 35. Three years later, in 1987, the high was 53 with a low of 26. The record warmest low of 43 was set back in 1915, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the past 33 highs (73%) were in the: 20s (12) and 30s (12). There were seven consecutive 20s & 30s highs from 1988 through 1994. On the warm side, six highs (18%) were in the: 40s (3), 50s (2) and 70s (1). O'Hare's only pre-1979 50s high was 52 in 1977. There have been no highs in the 60s for the date in O'Hare's history. On the cold side, three highs (9%) were in the 10s (a.k.a. teens). O'Hare had a high of 17 in 1967. This was the coldest high until 1981. In the 53 year history of O'Hare, only four highs were 50 degrees or higher. This is only 7.5% of the years which is on average once every 13.25 years.

In looking back through the years to the first February at O'Hare in 1959, the following instances were notable: In 1978 the low was a cold 4 degrees. In 1977 the high was 52 with a low of 34, a warm day. In 1976 the low was a warm 32 degrees. In 1974 the high was 36 with a cold low of 3, a 33 degree spread. In 1972 the high was 33 with a cold low of 3, a 30 degree spread. In 1971 the low was a warm 31 degrees. In 1968 the high was 20 with a low of 3, a cold day. In 1967 the high was 17 with a low of -1, a cold day. In 1964 the high was 39 with a low of 9, a 30 degree spread. In 1963 the high was 23 with a cold low of 5, a cold day. In 1960 the high was a cold 22 degrees.

More recently, there were small spreads of four degrees in 1985 (27/23) and five degrees in 1997 (26/21).

On the cold side, in 1981 the high was 10 with a low of -11. 1981 was O'Hare's coldest February 11th. In 2008 the high was 15 with a low of -3. In 1995 the high was 14 with a low of -1. In 1986 the high was 20 with a low of -1. Four years earlier, in 1982, the high was 20 with a low of 1. In 1994 the high was 25 with a low of -1. The other cold lows were 5 degrees in: 2003, 2007 and last year, 2011. The other cold highs were 20 in 1979 and 21 in 1980. The record low of -14 was set way back in 1885 and record coldest high of 1 occurred way back in 1899. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 20 of the last 33 lows (61%) were in the: 10s (a.k.a. teens) (10) and 20s (10). O'Hare had seven consecutive lows in the 10s & 20s from 1987 through 1993. Even colder, ten lows (30%) were in the: negative 10s (1), negative single digits (4) and single digits (5). On the warm side, three lows (9%) were in the 30s.

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 1986 the high was 20 with a low of -1, overall 16.5 degrees BELOW normal. Then in 1987 the high was 53 with a low of 26, overall 13.5 degrees ABOVE normal. In the second instance, in 2008 the high was 15 with a low of -3, overall 20 degrees BELOW normal. Then in 2009 the high was 50 with a low of 36, overall 17 degrees ABOVE normal.

Today is a major day in Chicago's snow history. In 1981, 1.5 inches fell. This was the third day of a three day, 11.6 inch storm. This storm comprised 73% of the month's total. In 1988, 4.3 inches fell. This was the second day of a two day, 9.1 inch storm.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:27 and sunrise is at 6:56. Sunset is at 17:20 and twilight ends at 17:49. There's a total of 10 hours, 24 minutes of daylight today and 11 hours, 22 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:25 and sunrise is at 6:54. The moon is waning gibbous. Illumination was 86% at midnight, will be 82% at noon and 77% at midnight tonight. Moonset is at 8:31 this morning. Moonrise is at 22:15 tonight. Moonset is at 9:05 tomorrow morning. Moonlight time is 10 hours, 16 minutes which is 42 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. Abraham Lincoln's Birthday is tomorrow. Valentine's Day is in three days. Susan B. Anthony Day is in four days.