January 17: ORD

Today is January 17th. It's the 17th day of the year. 349 days remain. It's week 3 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 15.

On the warm side, in 1996 the high was 56 with a low of 37 (our most recent 30s low). A decade earlier, in 1986, the high was 54 with a low of 37. Four years later, in 1990, the high was 55 with a low of 35. A decade before, in 1980, the high was 44 with a low of 35. In 1989 the high was 45 with a low of 30. A year earlier, in 1988, the high was 41 with a low of 33. In 1995 the high was 43 with a low of 30. In 2006 the high was 43 with a low of 27. The other warm low was 28 in 2004. The record high of 60 was set way back in 1894, at a time when the official readings were taken adjacent to Lake Michigan. The record warmest low of 42 occurred in 1973 at Midway. 25 of the past 33 highs (76%) were in the: 20s (12), 30s (7) and 40s (6). On the warm side, three highs were in the 50s. O'Hare's warmest for the date was 57 in 1973. On the cold side, five highs were in the: single digits (2) and 10s (aka teens) (3). O'Hare's coldest highs were 2 in 1962 and 4 in 1977.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: in 1977 the high was 4 with a low of -12, a cold day. In 1976 the high was 15 with a low of 1, a cold day. In 1974 the high was 36 with a warm low of 31, a five degree spread. In 1973 the high was 57 with a low of 43, a warm day and year of the record warmest low of 42 at Midway. In 1969 the high was 37 with a warm low of 35, a two degree spread and warm day. In 1967 the high was 14 with a low of -6, a cold day. In 1966 high was 10 with a low of -6, a cold day. In 1965 the low was a cold 2 degrees. In 1963 the high was 26 with a cold low of -12, a 38 degree spread and cold day. In 1962 the high was 2 with a low of -4, a six degree spread and cold day. In 1961 the high was 49 with a low of 28, a warm day. In 1959 the high was 11 with a low of -1, a cold day.

More recently, we had small spreads of four degrees in 1987 (29/25), six degrees in 2000 (25/19), six degrees in 2004 (34/28) and seven degrees in 2001 (26/19).

On the cold side, in 1982 the high was the former record coldest high of 4 with the record low of -23. Other lows in 1982 were as follows: Rockford: -25, Barrington and Marengo: -22, Elgin: -20, Wheaton, DeKalb and Waukegan: -18 and Midway: -17. In 1997 the high was the record coldest high of 3 with a low of -9. Three years earlier, in 1994, the high was 10 with a low of -13. In 2005 the high was 11 with a low of 2. In 1984 the high was 12 with a low of 2. The other cold low was 3 in 2009. 18 of the last 33 lows (55%) were in the: single digits (10) and 10s (a.k.a. teens) (8). On the warm side, 12 lows (36%) were in the: 20s (5) and 30s (7). O'Hare's warmest low (and only 40s low) was 43 in 1973. Three lows (9%) were in the cold: negative 20s (1), negative 10s (a.k.a. negative teens) (1) and negative single digits (1). The pre-1979 cold lows were -12 in 1963 and -12 in 1977.

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 1994 the high was 10 with a low of -13, overall 24.5 degrees BELOW normal. Then in 1995 the high was 43 with a low of 30, overall 13.5 degrees ABOVE normal. In the second instance, in 1996 the high was 56 with a low of 37, overall 23.5 degrees ABOVE normal. Then in 1997 the high was 3 with a low of -9, overall 26 degrees BELOW normal. In the third instance, in 2005 the high was 11 with a low of 2, overall 16.5 degrees below normal. Then in 2006 the high was 43 with a low of 27, overall 12 degrees ABOVE normal.

Today is a major day in O'Hare's snow history. In 1979, 1.2 inches fell. This was the seventh day of a 21.7 inch, seven day stretch of snow. This storm changed Chicago politics. The slow response that the city had to cleaning up after the storm was blamed on Mayor Michael Bilandic and his administration. This caused him to lose in the primary election to the eventual new mayor, Jayne Byrne. At O'Hare on the 13th, 15.3 inches fell while at Midway, 16.5 inches fell. This blizzard closed down the city for several days.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:48 and sunrise is at 7:19. Sunset is at 16:48 and twilight ends at 17:19. There's a total of 9 hours, 29 minutes of daylight today and 10 hours, 31 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 6:47 and sunrise is at 7:18. The moon is waning crescent, having passed last quarter yesterday at 3:08. Illumination was 40% at midnight, will be 35% at noon and 29% at midnight tonight. Moonrise was at 1:37 this morning. Moonset is at 11:41 this morning. Moonrise is at 2:48 tomorrow morning. Moonlight time is 10 hours, 4 minutes which is 33 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. National Freedom Day is in 15 days. Groundhog Day is in 16 days.