December 23: ORD

Today is December 23rd. It's the 358th day of the year. Eight days remain. It's week 52 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.

According to the National Climatic Data Center (NCDC), the normal high is 32 and the normal low is 18. The 30-year averages are 34 and 20.

On the warmer side, in 1979 the high was the co-record high of 62 with a low of 46. Three years later, in 1982, the high was the co-record high of 62 with a low of 42. In 1996 the high was 52 with a low of 32. In 1988 the high was 48 with a low of 33. In 2005 the high was 44 with a low of 37, a seven degree spread. In 1994 the high was 42 with a low of 35, a seven degree spread. Two years ago the high was 40 with a low of 33, a seven degree spread. In 1987 the high was 42 with a low of 30. Other warm highs were 52 last year and 43 in 1984. Other warmer lows were 32 in 1997 and 31 in 1980. The record warmest low of 49 was set in 1877. 18 of the last 30 highs were 30s (11) and 40s (7). On the warmer side, two highs were 50s and two highs were 60s. On the colder side, three highs were 20s, three highs were 10s, one high was in the 0s and one high was in the negative 0s.

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable. In 1975 the high was 34 with a low of 27, a seven degree spread. In 1972 the high was 32 with a low of 30, a two degree spread. In 1969 the high was 28 with a low of 24, a four degree spread. In 1963 the high was 22 with a low of -8, a 30 degree spread and cold! In 1961 the high was 31 with a low of 24, a seven degree spread. In 1960 the high was 11 with a low of -17, a very cold day. In 1959 the high was 29 with a low of 25, a four degree spread.

More recently, we had small spreads of five degrees in 1986 (34/29), five degrees in 1997 (37/32), seven degrees in 1980 (38/31) and seven degrees in 1995 (30/23). A large spread of 38 degrees occurred last year (52/14).

On the cold side, in 1983 the high was the record coldest high of -6 with a low of -21. Six years later, in 1989, the high was 8 with a low of -11. A year later, in 1990, the high was 11 with a low of 0. A decade later, in 2000, the high was 20 with a low of -4. A year earlier, in 1999, the high was 16 with a low of 3. Five years later, in 2004, the high was 18 with a low of 5. 16 of the last 30 lows were 20s (8) and 30s (8). On the warmer side, two lows were 40s. On the colder side, 12 of the 30 lows were 10s (4), 0s (5), negative zeros (1), negative 10s (1) and negative 20s (1).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:48 and sunrise is at 7:20. Chicago's sunrise and twilight times are each four minutes earlier. Sunset is at 16:26 and twilight ends at 16:58. Chicago's sunset and end of twilight times are two minutes and a minute earlier respectively. There's a total of 9 hours, 6 minutes of daylight today and 10 hours, 9 minutes between twilights. Tomorrow twilight begins at 6:48 and sunrise is at 7:20. The moon is waning crescent. Illumination was 16% at midnight, will be 12% at noon and 9% at midnight tonight. Moonrise was at 4:04 and moonset is at 13:24. Moonrise is at 5:07 tomorrow. Moonlight time is 9 hours, 20 minutes today. The Winter Solstice was two days ago at 6:04.

Today is a major snow day in O'Hare's history. In 1969, 9.9 inches fell. This was the third of four days of measurable snowfall, part of a total of 13.5 inches during the period. In 1961 at Midway, 10.2 inches fell while O'Hare had 7.4 inches, part of a three-day, 8.2 inch event. (half an inch fell on the 21st and 0.3 fell on the 22nd).

Christmas Eve is tomorrow and Christmas Day is in two days. New Year's Eve is in eight days and New Year's Day is in nine days. -Bernie-