February 5: ORD

Today is February 5th. It's the 36th day of the year. 330 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 32 and the normal low is 18. I've calculated the 33-year averages at 29 and 14.

On the warm side, in 2005 the high was 55 with a low of 36. That high of 55 shares the high of 55 in 1964 as O'Hare's warmest of the date. The low of 36 shares the low of 36 in 1973 as O'Hare's warmest lows of the date. In 1990 the high was 51 with a low of 30. The year later, 1991, the high was 50 with a low of 27. The other warm high was 49 in 1993. The other warm lows were 32 in 2008, 31 in 1986 and 30 two years ago in 2010. The record high of 56 was set back in 1946 at Midway. The record warmest low of 43 occurred back in 1938, at a time when the official readings were taken adjacent to Lake Michigan. 20 of the past 33 highs (61%) were in the: 20s (12) and 30s (8). On the warm side, seven highs (21%) were in the: 40s (4) and 50s (3). On the cold side, six highs (18%) were in the: single digits (3) and 10s (a.k.a. teens) (3).

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 12 with a low of -3, a cold day. In 1975 the high was 35 with a warm low of 29, a six degree spread. In 1974 the high was 25 with a low of 22, a three degree spread. In 1973 the high was 38 with a warm low of 36, a two degree spread and warm day. In 1972 the high was 23 with a cold low of -2, a cold day. In 1971 the high was a warm 46 degrees. In 1968 the high was a warm 47 degrees. In 1966 the high was 24 with a cold low of -1, a cold day. In 1964 the high was a warm 55 with a low of 28, a warm day. In 1963 the high was 42 with a low of 12, a 30 degree spread. In 1962 the high was 37 with a cold low of 5, a 32 degree spread. In 1960 the high was 39 with a warm low of 33, a six degree spread and warm day. In 1959 the high was 18 with a low of 3, a cold day.

More recently, there were small spreads of four degrees in 2004 (28/24), five degrees in 1986 (36/31), five degrees in 1997 (33/28), five degrees two years ago, in 2010 (35/30), six degrees in 1998 (35/29), and six degrees in 2001 (32/26).

On the cold side, in 1979 the high was 3 with a low of -14. Both the high and low were O'Hare's coldest of the date. In 2007 the high was 5 with a low of -10. In 1988 the high was 9 with a low of -1. Six years prior, in 1982, the high was 15 with a low of 1. In 1995 the high was 14 with a low of 3. Six years prior, in 1989, the high was 17 with a low of 1. Three years ago, in 2009, the high was 25 with a low of -4. In 1996 the high was 22 with a low of 2. In 1985 the high was 22 with a low of 4. Four years prior, in 1981, the high was 25 with a low of 1. The other cold lows were 4 last year, in 2011 and 6 in 1983. The record low of -17 was set in 1979 (at Midway). The record coldest high of 0 was set way back in 1936, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the last 33 lows (73%) were in the: single digits (9), 10s (a.k.a. teens) (6) and 20s (9). For 14 consecutive years, from 1991 through 2004, lows were in the single digits, 10s and 20s. Our most recent 10s low was 10 in 2002. Even colder, four lows (12%) were in the: negative 10s (a.k.a. negative teens) (2) and negative single digits (2). Five lows (15%) were in the warm 30s. Through Winter 2010-11, this is the average eighth coldest day of the year.

An interesting fact concerning what happened three years ago: The National Weather Service/Chicago reports that January 2009 was just the tenth January (in 137 years of record-keeping) that no temperature reached 40 degrees. The last time this happened was in 1985. This also occurred in 1982, 1979, 1977, 1976, 1920, 1918, 1912 and 1904. January 1977 was a bit worse, since the temperatures that year never got to the freezing mark (32 degrees).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1989 the high was 17 with a low of 1, overall 16 degrees BELOW normal. Then in 1990 the high was 51 with a low of 30, overall 15.5 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:33 and sunrise is at 7:03. Sunset is at 17:12 and twilight ends at 17:42. There's a total of 10 hours, 9 minutes of daylight today and 11 hours, 9 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:32 and sunrise is at 7:02. The moon is waxing gibbous, heading towards the full Snow (a.k.a. Hunger) moon in two days at 15:54. Illumination was 92% at midnight, will be 94% at noon and 97% at midnight tonight. Moonset was at 5:15 this morning. Moonrise was at 15:10 this afternoon. Moonset is at 5:54 tomorrow morning. Moonlight time is 14 hours, 5 minutes which is 20 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 seven days. Valentine's Day is in nine days. Susan B. Anthony Day is in ten days.