January 20: ORD

Today is January 20th. It's the 20th day of the year. 346 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 28 and 14.

On the warm side, in 2006 the high was 46 (with 1967's high of 46, O'Hare's warmest highs of the date) with a low of 32. In 1990 the high was 39 with a low of 33, a six degree spread. Two years earlier, in 1988, the high was 38 with a low of 31, a seven degree spread. The other warm high was 44 in 1981. The other warm low was 32 in 1979. The record high of 63 was set way back in 1906 and the record warmest low of 45 was set back in 1921. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 24 of the past 33 highs (73%) were in the: 20s (9) and 30s (15). There were eight consecutive highs in the 20s & 30s from 1986 through 1993. On the warm side, three highs were in the 40s. On the cold side, six highs were in the: negative single digits (1), single digits (1) and 10s (a.k.a. teens) (4).

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: in 1975 the low was a cold 4 degrees. In 1974 the high was 42 with a warm low of 35, a seven degree spread and warm day. In 1971 the high was 29 with a cold low of -2, a 31 degree spread. In 1970 the high was 1 with a low of -10, a cold day. In 1969 the high was a warm 45 with a low of 24, a warm day. In 1968 the high was 42 with a low of 27, a warm day. In 1967 the high was a warm 46 with a low of 25, a warm day and part of the pre-blizzard of '67 warm-up. In 1966 the low was a cold 3 degrees. In 1964 the high was 44 with a low of 34, a warm day. In 1963 the high was 5 with a low of -10, a cold day. In 1962 the high was 20 with a cold low of -3, a cold day. In 1960 the high was a cold 17 with a low of 6, a cold day.

More recently, we had small spreads of 4 degrees in 1979 (36/32), 5 degrees in 2005 (28/23) and 7 degrees in 1995 (33/26).

On the cold side, in 1985 the high was the record coldest high of -4 with the record low of -27. That low of -27 was the coldest reading ever at O'Hare/Chicago. A year earlier, in 1984, the high was 0 with a low of -20. A decade later, in 1994, the high was 15 with a low of -12. In 2008 the high was 10 with a low of -5. In 2000 the high was 19 with a low of 0. The other cold high of 11 occurred last year, in 2011. 21 of the last 33 lows (64%) were in the: 10s (a.k.a. teens) (13) and 20s (8). On the cold side, eight lows were in the: negative 20s (2), negative 10s (a.k.a. negative teens) (1), negative single digits (1) and single digits (4). Four lows were in the warm 30s. Through Winter 2010-11, this is the average fourth coldest day of the year.

Today is a major day in O'Hare's snow history. In 2005, 1.5 inches fell. This was the first day of a four day, 12.7 inch period of snow. Along with the 9.8 inches that fell earlier on January 4-6, this comprised 22.5 inches or 81% of the month's total of 27.8 inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:46 and sunrise is at 7:17. Sunset is at 16:52 and twilight ends at 17:22. There's a total of 9 hours, 35 minutes of daylight today and 10 hours, 36 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:46 and sunrise is at 7:16. The moon is waning crescent, three days from new. Illumination was 11% at midnight, will be 8% at noon and 5% at midnight tonight. Moonrise is at 4:55 this morning. Moonset is at 14:22 this afternoon. Moonrise is at 5:48 tomorrow morning. Moonlight time is 9 hours, 27 minutes which is a minute 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 12 days. Groundhog Day is in 13 days.