February 15: ORD

Today is February 15th. It's the 46th day of the year. 320 days remain. It's week 7 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 35 and the normal low is 20. I've calculated the 33-year averages at 34 and 21.

On the warm side, in 1984 the high was 60 with a low of 33. In 1999 the high was 55 with a low of 34. A year earlier, in 1998, the high was 53 with a low of 32. The other warm lows were: 35 in 2002, 34 in 1982, 33 in 1981, 33 in 1992, 33 in 2005 and 32 in 2006. The record high of 69 was set in 1954 at Midway. The record warmest low of 43 occurred in 1976 at Midway. A warm low of note was 40 in 1954 at Midway. 26 of the past 33 highs (79%) were in the: 20s (7), 30s (12) and 40s (7). On the warm side, three highs (9%) were in the: 50s (2) and 60s (1). O'Hare's warmest high was 65 in 1976. The other warm high was 59 in 1961. On the cold side, four highs (12%) were in the 10s (a.k.a. teens). Prior to 1979, O'Hare had a cold high of 18 in 1963. O'Hare had a total of five days of 50 degrees or higher over it's 53 year history today. This represents only 9.4% or an average of 10.6 years between such occurrences.

In looking back through the years to the first February at O'Hare in 1959, the following instances were notable: In 1978 the high was a cold 22 with a low of 8, a cold day. In 1976 the high was 65 with a low of 40, a warm day and year of the record warmest low of 43 at Midway. In 1975 the high was 34 with a low of 27, a seven degree spread. In 1969 the high was 30 with a low of 25, a five degree spread. In 1967 the high was a warm 49 with a low of 13, a 36 degree spread. In 1963 the high was 18 with a low of -9, a cold day. In 1962 the high was 34 with a low of 29, a five degree spread. In 1961 the high was a warm 59 with a low of 28, a 31 degree spread and warm day.

More recently, there were small spreads of four degrees in 1992 (37/33), five degrees in 1990 (32/27), six degrees in 1987 (26/20), six degrees in 2001 (32/26), seven degrees in 1979 (27/20) and seven degrees in 2002 (42/35).

On the cold side, in 1985 the high was 12 (O'Hare's coldest high of the date) with a low of 0. Six years later, in 1991, the high was 13 with a low of 3. In 2007 the high was 14 with a low of 2. In 1986 the high was 18 with a low of -1. In 2004 the high was 22 with a low of 6. In 2008 the high was 24 with a low of 9. The other cold low was 6 in 2010 (two years ago). The record low of -9 was set way back in 1905 (after first being set way back in 1875) and the record coldest high of 5 was set back in 1920. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 27 of the last 33 lows (82%) were in the: 10s (a.k.a. teens) (9), 20s (9) and 30s (9). O'Hare's warmest low of the date was 40 in 1976. Even colder, six lows (18%) were in the: negative single digits (1) and single digits (5). O'Hare's coldest reading of the date was -9 in 1963.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1984 the high was 60 with a low of 33, overall 18.5 degrees ABOVE normal. Then in 1985 the high was 12 with a low of 0, overall 22 degrees BELOW normal.

Today is a major day in Chicago's snow history. In 1990, 1.4 inches fell. This was the second day of a two day, 9.7 inch storm known as the Valentine's Day Blizzard. This storm comprised 71% of the month's total of 13.6 inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:21 and sunrise is at 6:50. Sunset is at 17:25 and twilight ends at 17:54. There's a total of 10 hours, 35 minutes of daylight today and 11 hours, 33 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:20 and sunrise is at 6:49. The moon is waning crescent, having reached last quarter yesterday at 11:04. Illumination was 44% at midnight, will be 38% at noon and 33% at midnight tonight. Moonrise is at 1:47 this morning. Moonset is at 11:17 this morning. Moonrise is at 2:48 tomorrow morning. Moonlight time is 9 hours, 30 minutes which is 17 minutes shorter than yesterday. Moonlight time is at it's least today and tomorrow.

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. Susan B. Anthony Day is today. President's Day is in five days.