January 7: ORD

Today is January 7th. It's the 7th day of the year. 359 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 29 and 15.

On the warm side, in 2008 the high was the record high of 65 with the record warmest low of 51. The former record high of 59 occurred in 1907 (adjacent to Lake Michigan) and the former record warmest low of 44 occurred in 1965 at Midway. In 1989 the high was 53 with a low of 22, a 31 degree spread. In 1998 the high was 40 with a low of 35, a five degree spread. In 2003 the high was 47 with a low of 26. The other warm lows were 33 in 1992, 31 in 1987 and 30 in 1985. 21 of the past 33 highs (64%) were in the: 20s (14) and 30s (7). On the warm side, six highs (18%) were in the: 40s (4), 50s (1) and 60s (1). Until 2008, O'Hare's warmest high was 55 in 1965. On the cold side, six highs (18%) were in the: single digits (3) and 10s (a.k.a. teens) (3). O'Hare's coldest highs of 5 degrees occurred in both 1968 and 1970.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: In 1978 the high was 39 with a warm low of 34, a five degree spread, a warm day. In 1977 the high was 11 with a low of 0, a cold day. In 1976 the high was 31 with a cold low of -3, a 34 degree spread. In 1975 the high was 40 with a warm low of 31, a warm day. In 1974 the high was 9 with a low of -1, a cold day. In 1971 the high was 11 with a low of -3, a cold day. In 1970 the high was 5 with a low of -10, a cold day. In 1969 the high was a cold 15 with a low of 8, a cold day. In 1968 the high was 5 with a low of -13, a cold day. In 1965 the high was 55 with a low of 44, a warm day. In 1961 the low was a warm 29 degrees. In 1960 the high was 41 with a warm low of 31, a warm day.

More recently, we had a small spreads of three degrees in 1985 (33/30), four degrees in 1992 (37/33), six degrees in 1987 (37/31) and six degrees two years ago, in 2010 (22/16). There were no other large spreads aside from 1989 (on the warm side) and 1994 (on the cold side).

On the cold side, in 1986 the high was 9 with a low of -9. In 1999 the high was 9 with a low of -7. In 1982 the high was 8 with a low of -6. In 1988 the high was 14 with a low of -9. In 1979 the high was 16 with a low of -3. A couple of years later, in 1981, the high was 16 with a low of 4. In 1994 the high was 28 with a low of -4, a spread of 32 degrees. The record low of -16 was set way back in 1912. The record coldest high of -4 was set in 1942. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 17 of the last 33 lows (52%) were in the: 10s (a.k.a. teens) (9) and 20s (8). 11 lows (33%) were in the: negative single digits (6) and single digits (5). O'Hare's coldest low was -13 in 1968. The only other negative 10s (a.k.a. negative teens) low was -10 in 1970. Five lows (15%) were in the: 30s (4) and 50s (1). O'Hare had a low of 44 in 1965, it's only 40s low. Through Winter 2010-11, this is the average fourteenth coldest day of the year.

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 1988 the high was 14 with a low of -9, overall 21.5 degrees BELOW normal. Then in 1989 the high was 53 with a low of 22, overall 13.5 degrees ABOVE normal. In the second instance, in 1998 the high was 40 with a low of 35, overall 13.5 degrees ABOVE normal. Then in 1999 the high was 9 with a low of -7, overall 23 degrees BELOW normal.

Today is a major snow day in O'Hare's history. In 1962, 2.1 inches fell. This was the third day of a three day, 11 inch snowstorm.

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 16:37 and twilight ends at 17:09. There's a total of 9 hours, 15 minutes of daylight today and 10 hours, 18 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 6:50 and sunrise is at 7:22 (the latest sunrise of the year). The moon is waxing gibbous, heading towards the full Wolf (a.k.a. Old) moon in two days at 0:15. Illumination was 96% at midnight, will be 97% at noon and 99% at midnight tonight. Moonset was at 5:54 this morning. Moonrise was at 15:21 this afternoon. Moonset is at 6:40 tomorrow morning. Moonlight time is 9 hours, 27 minutes which is three 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. Martin Luther King, Jr. Day is in nine days.