February 3: ORD

Today is February 3rd. It's the 34th day of the year. 332 days remain. It's week 5 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 32 and the normal low is 17. I've calculated the 33-year averages at 31 and 16.

On the warm side, in 1992 the high was the record high of 59 with a low of 27, a 32 degree spread. The year prior, 1991, the high was 50 with a low of 34. These were O'Hare's only 50s highs for the date! In 1999 the high was 46 with a low of 35 (O'Hare's warmest low of the date). Four years later, in 2003, the high was 45 with a low of 32. Three years after that, in 2006, the high was 44 (our most recent 40s high) with a low of 32 (our most recent 30s low). The other warm highs were 46 in 1993 and 44 in 2005. The other warm lows were 30 (1984 & 1986) and 29 (1990 & 2000). The record warmest low of 37 occurred way back in 1890, at a time when the official readings were taken adjacent to Lake Michigan. 25 of the past 33 highs (76%) were in the: 20s (7), 30s (11) and 40s (7). On the warm side, two highs (6%) were in the 50s. On the cold side, six highs (18%) were in the: negative single digits (1) and 10s (a.k.a. teens) (5). There have been no highs in the single digits since the high of 2 in 1970.

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 21 with a cold low of 5, a cold day. In 1977 the high was 31 with a low of 28, a three degree spread. In 1976 the high was 31 with a cold low of -5, a 36 degree spread. In 1973 the high was 42 with a warm low of 31, a warm day. In 1970 the high was 2 with a low of -6, a cold day. In 1967 the high was 26 with a low of 20, a six degree spread. In 1965 the high was 6 with a low of -9, a cold day. In 1963 the high was 15 with a low of -8, a cold day. In 1962 the high was 36 with a warm low of 29, a seven degree spread.

More recently, there were small spreads of four degrees in 1986 (34/30), six degrees in 1984 (36/30), six degrees in 1990 (35/29) and seven degrees in 2008 (32/25).

On the cold side, in 1996 the high was the record coldest high of -5 with the record low of -19. In 1985 the high was 15 with a low of -12. In 2007 the high was 11 with a low of -6. In 1981 the high was 10 with a low of -5. Last year, in 2011, the high was 16 with a low of -6. In 1994 the high was 19 with a low of 1. Three years ago, in 2009, the high was 20 with a low of 1. Two decades prior, in 1989, the high was 22 with a low of 4. In 1980 the high was 25 with a low of 2. 28 of the last 33 lows (85%) were in the: single digits (6), 10s (a.k.a. teens) (6), 20s (10) and 30s (6). On the cold side, five lows were in the: negative 10s (a.k.a. negative teens) (2) and negative single digits (3).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2006 the high was 44 with a low of 32, overall 13 degrees ABOVE normal. Then in 2007 the high was 11 with a low of -6, overall 22.5 degrees BELOW normal.

Today is a major day in Chicago's snow history. These happened just five years apart from each other a long time ago and both at the Auditorium Tower. In 1896, 11.0 inches fell and in 1901, 10.8 inches fell. Nearly identical amounts.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:35 and sunrise is at 7:05. Sunset is at 17:10 and twilight ends at 17:39. There's a total of 10 hours, 5 minutes of daylight today and 11 hours, 4 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:34 and sunrise is at 7:04. The moon is waxing gibbous. Illumination was 78% at midnight, will be 82% at noon and 86% at midnight tonight. Moonset was at 3:43 this morning. Moonrise was at 13:09 this afternoon. Moonset is at 4:31 tomorrow morning. Moonlight time is 14 hours, 34 minutes which is 1 minute longer than yesterday. Moonlight time is at its peak right now.

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 nine days. Valentine's Day is in 11 days. Susan B. Anthony Day is in 12 days.