February 10: ORD

Today is February 10th. It's the 41st day of the year. 325 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 31 and 16.

On the warm side, three years ago, in 2009, the high was 61 with a low of 41. 2009 was O'Hare's warmest February 10th. In 1996 the high was 53 with a low of 36. Three years later, in 1999, the high was 60 with a low of 28, a 32 degree spread. These two highs in the 60s are the only 60s highs in O'Hare history for the date. A year earlier, in 1998, the high was 48 with a low of 30 (our most recent 30s low). The other warm highs were 46 in both 1987 and 2002 (our most recent 40s high). The other warm lows were 35 in 1984 and 33 in 1993. The record high of 63 was set way back in 1876. The record warmest low of 43 was set way back in 1886. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 19 of the past 33 highs (58%) were in the: 20s (9) and 30s (10). On the warm side, eight highs (24%) were in the: 40s (5), 50s (1) and 60s (2). Prior to 1979, O'Hare's 50s highs were 58 in 1976, 53 in 1966 and 52 in 1965. On the cold side, six highs (18%) were in the: single digits (1) and 10s (a.k.a. teens) (5). Highs in the 50s or 60s have occurred only six times in O'Hare's 53-year history on this date. This represents 11% or about one every 8 and five/sixths 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 5 degrees. In 1977 the high was a warm 47 with a low of 28, a warm day. In 1976 the high was 58 with a low of 39, a warm day. In 1975 the high was 22 with a low of -2, a cold day. In 1972 the high was a cold 21 degrees. In 1968 the high was 15 with a low of 2, a cold day. In 1966 the high was 53 with a low of 31, a warm day. In 1965 the high was a warm 52 with a low of 25, a warm day. In 1962 the high was 24 with a low of 17, a seven degree spread.

More recently, there were small spreads of four degrees in 1983 (30/26), four degrees in 1984 (39/35), five degrees in 1993 (38/33) and six degrees in 1997 (30/24).

On the cold side, in 1982 the high was 5 with a low of -12. 1982 was O'Hare's coldest February 10th. Last year, in 2011, the high was 16 with a low of -9. Three years prior, in 2008, the high was 16 with a low of -4. A year before that, in 2007, the high was 13 with a low of -1. In 1979 the high was 12 with a low of 0. In 1994 the high was 21 with a low of -8. In 1986 the high was 18 with a low of -2. In 1980 the high was 21 with a low of 4. The other cold low was 6 in 1989. The other cold highs were 20 in both 1988 and 2001. The record low of -18 and record coldest high of -1 were set on the same cold day way back in 1899, at a time when the official readings were taken adjacent to Lake Michigan. 12 of the last 33 lows (36%) were in the 20s. On the cold side, 16 lows (49%) were in the: negative 10s (1), negative single digits (5), single digits (5) and 10s (a.k.a. teens) (5). Our most recent single digit low was 8 in 2003. Prior to 1982, O'Hare's coldest low was -2 in 1975. On the warm side, five lows (15%) were in the: 30s (4) and 40s (1). Until 2009, O'Hare's warmest low was 39 in 1976.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2008 the high was 16 with a low of -4, overall 20 degrees BELOW normal. Then in 2009 the high was 61 with a low of 41, overall 25 degrees ABOVE normal.

Today is a major day in Chicago's snow history. In 1981, 9.7 inches fell. This was the second day of a three day, 11.6 inch storm. This storm comprised 73% of the month's total. In 1988, 4.8 inches fell. This was the first 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 6:28 and sunrise is at 6:57. Sunset is at 17:19 and twilight ends at 17:48. There's a total of 10 hours, 22 minutes of daylight today and 11 hours, 20 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:27 and sunrise is at 6:56. The moon is waning gibbous. Illumination was 93% at midnight, will be 90% at noon and 86% at midnight tonight. Moonset is at 8:00 this morning. Moonrise is at 21:02 tonight. Moonset is at 8:31 tomorrow morning. Moonlight time is 10 hours, 58 minutes which is 43 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 in two days. Valentine's Day is in four days. Susan B. Anthony Day is in five days.