January 23: ORD

Today is January 23rd. It's the 23rd day of the year. 343 days remain. It's week 4 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 31 and the normal low is 16. I've calculated the 33-year averages at 32 and 18.

On the warm side, in 1989 the high was 50 with a low of 33. In 2002 the high was 48 with a low of 35. In 1990 the high was 50 with a low of 28. Two years ago, in 2010, the high was 44 with a low of 34. In 1999 the high was 44 with a low of 33. In 1981 the high was 46 with a low of 27. In 1993 the high was 45 with a low of 28. The next year, 1994, the high was 40 with a low of 33, a seven degree spread. The other warm lows were 32 in 1983 and 29 in 1996. The record high of 65 and record warmest low of 56 were set on the same warm day way back in 1909, at a time when the official readings were taken adjacent to Lake Michigan. 27 of the past 33 highs (82%) were in the: 20s (7), 30s (13) and 40s (7). On the warm side, two highs were in the 50s. O'Hare's warmest highs of the date were 60 in 1967 and 52 in 1969. On the cold side, four highs were in the: single digits (1) and 10s (a.k.a. teens) (3). O'Hare's coldest high of the date was -6 in 1963.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: in 1974 the high was 35 with a warm low of 30, a five degree spread. In 1970 the high was 21 with a cold low of 3, a cold day. In 1969 the high was a warm 52 with a low of 19, a 33 degree spread and a warm day. In 1967 the high was 60 with a low of 45, a warm, pre-blizzard day. In 1966 the high was 20 with a cold low of -4, a cold day. In 1965 the high was 34 with a warm low of 30, a four degree spread. In 1964 the high was 48 with a low of 34, a warm day. In 1963 the high was -6 with a low of -19, a cold day. 1963 was the year of the record low of -18 and record coldest high of -4. In 1962 the high was 20 with a cold low of 0, a cold day. In 1961 the high was 21 with a cold low of -5, a cold day. In 1959 the high was 6 with a low of -12, a cold day.

More recently, we had small spreads of two degrees in 1983 (34/32), four degrees in 2007 (26/22), seven degrees in 1996 (36/29) seven degrees in 2006 (30/23) and a big 36 degree spread in 1982 (38/2).

On the cold side, in 1987 the high was 8 with a low of -4. In 2003 the high was 12 with a low of -4. Five years later, in 2008, the high was 14 with a low of 5. In 1980 the high was 15 with a low of 4. Last year, in 2011, the high was 20 with a low of 4. The other cold lows were 2 in 1982 and 3 in 2000. The record low of -18 and record coldest high of -4 were set on the same cold day in 1963 at Midway. 31 of the last 33 lows (94%) were in the: single digits (7), 10s (a.k.a. teens) (7), 20s (11) and 30s (6). O'Hare's warmest low of the date was 45 in 1967. This was O'Hare's only 40s low of the date. On the cold side, two lows were in the negative single digits. O'Hare's coldest lows of the date were -19 in 1963 and -12 in 1959.

There were three instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1980 the high was 15 with a low of 4, overall 14.5 degrees BELOW normal. Then in 1981 the high was 46 with a low of 27, overall 12.5 degrees ABOVE normal. In the second instance, in 2002 the high was 48 with a low of 35, overall 17.5 degrees ABOVE normal. Then in 2003 the high was 12 with a low of -4, overall 20 degrees BELOW normal. In the third instance, in 2010 the high was 44 with a low of 34, overall 15 degrees ABOVE normal. Then in 2011 (last year) the high was 20 with a low of 4, overall 12 degrees BELOW normal.

Today is a major day in O'Hare's snow history. In 2005, 0.2 inches fell. This was the fourth day of a four day, 12.7 inch period of snow. Along with the 9.8 inches that fell earlier on January 4-6, this comprised 22.5 inches or 81% of the month's total of 27.8 inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:45 and sunrise is at 7:15. Sunset is at 16:56 and twilight ends at 17:26. There's a total of 9 hours, 41 minutes of daylight today and 10 hours, 41 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:44 and sunrise is at 7:14. The moon is new today at 1:39. Illumination was 0% at midnight, will be 0% at noon and 1% at midnight tonight. Moonrise is at 7:09 this morning. Moonset is at 17:45 this afternoon. Moonrise is at 7:41 tomorrow morning. Moonlight time is 10 hours, 36 minutes which is 32 minutes longer 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. National Freedom Day is in nine days. Groundhog Day is in ten days.