January 25: ORD

Today is January 25th. It's the 25th day of the year. 341 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 30 and 14.

On the warm side, in 1981 the high was 51 with a low of 37. Eight years later, in 1989, the high was 49 with a low of 37. Those lows of 37 were O'Hare's warmest lows of the date. In 2002 the high was 50 with a low of 27. The other warm high was 43 in 2005. The record high of 67 was set in 1950 at Midway. The record warmest low of 45 occurred back in 1916, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the past 33 highs (73%) were in the: 20s (10) and 30s (14). There were ten consecutive highs in the 20s & 30s from 1992 through 2001. On the warm side, four highs (12%) were in the: 40s (2) and 50s (2). O'Hare had a high of 51 in 1967 and its warmest of the date was 54 in 1973. On the cold side, five highs (15%) were in the 10s (a.k.a. teens). O'Hare's coldest highs of the date are 8 in 1963 and 9 in 1972.

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 48 with a low of 29, a warm day. In 1973 the high was 54 with a low of 31, a warm day. In 1972 the high was 9 with a low of 1, a cold day. In 1971 the high was a warm 44 with a low of 10, a 34 degree spread. In 1970 the high was 39 with a warm low of 32, a seven degree spread and warm day. In 1969 the high was 12 with a low of 3, a cold day. In 1967 the high was 51 with a low of 30, a warm, pre-blizzard day. In 1966 the low was a cold 4 degrees. In 1963 the high was 8 with a low of -9, a cold day. In 1961 the high was 16 with a low of -8, a cold day. In 1959 the high was 26 with a low of 19, a seven degree spread.

More recently, there were no small spreads, unusual for any day. In 1988 the spread was 31 degrees as the high was 29 with a low of -2.

On the cold side, in 1982 the high was 10 with a low of -1. Three years ago, in 2009, the high was 13 with a low of -2. A year before, in 2008, the high was 20 with a low of -5. In 1991 the high was 16 with a low of -1. Four years earlier, in 1987, the high was 19 with a low of -1. In 1979 the high was 18 with a low of 4. The other cold lows were -2 in 1988, -1 in 1985 and 1 in 1997 (our most recent single digit low). The record low of -20 and record coldest high of -10 were set on the same cold day way back in 1897, at a time when the official readings were taken adjacent to Lake Michigan. 19 of the last 33 lows (58%) were in the: 10s (a.k.a. teens) (8) and 20s (11). There were ten consecutive lows in the 10s & 20s from 1998 through 2007. 12 lows (36%) were in the cold: negative single digits (7) and single digits (5). O'Hare's coldest lows were -9 in 1963 and -8 in 1961. Two lows (6%) were in the warm 30s. Through Winter 2010-11, this is the average thirteenth coldest day of the year.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1981 the high was 51 with a low of 37, overall 20 degrees ABOVE normal. Then in 1982 the high was 10 with a low of -1, overall 19.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:43 and sunrise is at 7:13. Sunset is at 16:58 and twilight ends at 17:28. There's a total of 9 hours, 45 minutes of daylight today and 10 hours, 45 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:42 and sunrise is at 7:13. The moon is waxing crescent, having passed new two days ago at 1:39. Illumination was 4% at midnight, will be 7% at noon and 9% at midnight tonight. Moonrise is at 8:09 this morning. Moonset is at 19:55 tonight. Moonrise is at 8:35 tomorrow morning. Moonlight time is 11 hours, 46 minutes which is 36 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 seven days. Groundhog Day is in eight days.