January 10: ORD

Today is January 10th. It's the 10th day of the year. 356 days remain. It's week 2 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 2000 the high was 46 with a low of 37. Two years later, in 2002, the high was 44 with a low of 34. In 1983 the high was 41 with a low of 35, a six degree spread. In 2008 the high was 44 with a low of 32. The other warm high was 52 in 1980, O'Hare's only 50s high for the date. The other warm lows were 29 (in 1987, 1990 and 2005). Both records were established in 1975. That year registered a high of 60 with a low of 42 at Midway. 21 of the past 33 highs (64%) were in the: 20s (8) and 30s (13). O'Hare had nine consecutive 20s & 30s highs from 1989 through 1997. On the warm side, five highs (15%) were in the: 40s (4) and 50s (1). On the cold side, seven highs (21%) were in the: negative single digits (1), single digits (1) and 10s (a.k.a. teens) (5). O'Hare's warmest high was 60 in 1975, the same day and temperature of the record high established at Midway.

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 8 with a low of -7, a cold day. In 1977 the high was 19 with a low of -2, a cold day. In 1976 the low was a cold 5 degrees. In 1975 the high was 60 with a low of 41. Midway's high was also 60 (the record) but at Midway the low was a degree higher at 42, the record warmest low. In 1973 the high was 19 with a low of 0, a cold day. In 1972 the high was 46 with a low of 31, a warm day. In 1970 the high was 17 with a low of -4, a cold day. In 1969 the high was 15 with a low of -3, a cold day. In 1964 the high was 20 with a cold low of 5, a cold day. In 1963 the low was a warm 30 degrees. In 1962 the high was 4 with a low of -15, a cold day. In 1960 the low was a warm 29 degrees. In 1959 the low was a cold 3 degrees.

More recently, we had four days of small spreads. One was five degrees: 34/29 in 1987. Three others were six degrees: 25/19 in 1985, 27/21 in 1993 and 35/29 in 2005. The lone large spread of 36 degrees occurred in 1980 with O'Hare's only 50s high of 52 and a low of 16.

On the cold side, in 1982 the high was the record coldest high of -4 with the record low of -26. The low at Rockford was -27. Three years earlier, in 1979, the high was 2 with a low of -13. In 1988 the high was 15 with a low of -12. A decade and a year later, in 1999, the high was 14 with a low of -2. In 1981 the high was 16 with a low of -2. Three years later, in 1984, the high was 20 with a low of -4. Two years ago, in 2010, the high was 18 with a low of 0. In 1998 the high was 17 with a low of 7. 20 of the last 33 lows (61%) were in the: 10s (a.k.a. teens ) (11) and 20s (9). There were eight consecutive 10s & 20s lows from 1989 through 1996. Nine lows (27%) were in the cold: negative 20s (1), negative 10s (a.k.a. negative teens) (2), negative single digits (3) and single digits (3). Four lows (12%) were in the warm 30s. O'Hare's warmest low was 41 in 1975. Through Winter 2010-11, this is the average eighth 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 1983 the high was 41 with a low of 35, overall 14 degrees ABOVE normal. Then in 1984 the high was 20 with a low of -4, overall 16 degrees BELOW normal. In the second instance, in 1999 the high was 14 with a low of -2, overall 18 degrees BELOW normal. Then in 2000 the high was 46 with a low of 37, overall 17.5 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:50 and sunrise is at 7:21. Sunset is at 16:40 and twilight ends at 17:12. There's a total of 9 hours, 19 minutes of daylight today and 10 hours, 22 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:50 and sunrise is at 7:21. The moon is waning gibbous, having reached the full Wolf (a.k.a. Old) moon yesterday morning at 0:15. Illumination was 99% at midnight, will be 98% at noon and 96% at midnight tonight. Moonset is at 7:57 this morning. Moonrise is at 18:35 tonight. Moonset is at 8:30 tomorrow morning. Moonlight time is 10 hours, 38 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. Martin Luther King, Jr. Day is in six days.