January 4: ORD

Today is January 4th. It's the 4th day of the year. 362 days remain. It's week 1 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 17. I've calculated the 33-year averages at 32 and 17.

On the warm side, in 1997 the high was the record high of 64 with a near-record warmest low of 39. A decade later, in 2007, the high was 52 with a near-record warmest low of 39. The record warmest low remains 41 degrees, set way back in 1909, at a time when the official readings were taken adjacent to Lake Michigan. In 1998 the high was 56 with a low of 34. In 2006 the high was 43 (O'Hare's most recent 40s high) with a low of 36, a seven degree spread. In 1993 the high was 47 with a low of 31. In 1990 the high was 46 with a low of 25. The other warm lows were 32 in 1992, 30 in 2005 and 29 in 2004. 17 of the past 33 highs (52%) were in the 30s. O'Hare had six consecutive 30s highs from 2000 through 2005. On the warm side, six highs (18%) were in the: 40s (3), 50s (2) and 60s (1). Before 1997/1998, O'Hare didn't have a high of 50 or higher. On the cold side, ten highs (30%) were in the: single digits (4), 10s (a.k.a. teens) (2) and 20s (4). Our most recent 20s high was 25 in 1996. O'Hare's coldest high was 0 in 1959.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: in 1977 the low was a cold 5 degrees. In 1976 the high was 10 with a low of 1, a cold day. In 1974 the high was 19 with a low of -1, a cold day. In 1972 the high was 14 with low of 2, a cold day. In 1971 the high was a warm 43 with a low of 12, a 31 degree spread. In 1970 the low was a cold 3 degrees. In 1969 the high was 3 with a low of -8, a cold day. In 1968 the high was 6 with a low of -7, a cold day. In 1967 the low was a cold 2 degrees. In 1966 the high was a warm 45 with a low of 26, a warm day. In 1963 the high was 34 with a low of 27, a seven degree spread. In 1962 the high was 42 with a warm low of 31, a warm day. In 1961 the high was 32 with a cold low of 1, a 31 degree spread. In 1959 the high was 0 with a low of -10, a cold day.

More recently, we had small spreads of four degrees in 1980 (30/26), four degrees in 2004 (33/29), five degrees in 2005 (35/30) and six degrees in 1992 (38/32).

On the cold side, in 1981 the high was 5 with a low of -9. In 1999 the high was 5 with a low of -9 as well (our most recent: single digit high and negative low). In 1979 the high was 4 with a low of -7. In 1995 the high was 7 with a low of -1. In 1988 the high was 19 with a low of -9. Two years ago, in 2010, the high was 18 with a low of 7. The other cold lows were 1 in 1985 and 3 in 1991. The record low of -14 and record coldest high of -6 were set on the same cold day way back in 1884, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the last 33 lows (73%) were in the: 10s (a.k.a. teens) (10), 20s (7) and 30s (7). Nine lows (27%) were in the cold: negative single digits (5) and single digits (4). O'Hare's coldest low was -10 in 1959. With a high of 0 in 1959, 1959 was O'Hare's coldest January 4th.

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1990 the high was 46 with a low of 25, overall 11.5 degrees ABOVE normal. Then in 1991 the high was 24 with a low of 3, overall 10.5 degrees BELOW normal. In the second instance, in 1998 the high was 56 with a low of 34, overall 21 degrees ABOVE normal. Then in 1999 the high was 5 with a low of -9, overall 26 degrees BELOW normal.

Today is a major snow day in O'Hare's history. In 2005, 1.2 inches fell. This was the first day of a three day, 9.8 inch storm.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:51 (the latest start to twilight) and sunrise is at 7:22 (the latest sunrise of the year). Sunset is at 16:34 and twilight ends at 17:06. There's a total of 9 hours, 12 minutes of daylight today and 10 hours, 15 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 6:51 (the latest start to twilight) and sunrise is at 7:22 (the latest sunrise of the year). The moon is waxing gibbous. Illumination was 77% at midnight, will be 81% at noon and 84% at midnight tonight. Moonset was at 3:09 this morning. Moonrise is at 12:57 this afternoon. Moonset is at 4:07 tomorrow morning. Moonlight time is 9 hours, 48 minutes which is 23 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. Martin Luther King, Jr. Day is in 12 days.