December 24: ORD

Today is December 24th. It's the 358th day of the year. Seven 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 32-year averages are 30 and 15.

On the warmer side, in 1982 the high was the near-record high of 62 with the record warmest low of 51. The record high of 64 remains, having being set way back in 1889. Three years earlier, in 1979, the high was 51 with a low of 37. In 1987 the high was 48 with a low of 34. In 2005 the high was 39 with a low of 34, a five degree spread. A year later, in 2006, the high was 44 with a low of 29. Other warm lows were 33 in 1997 and 32 last year. 29 of the last 32 highs (91%) were: 10s (5), 20s (10), 30s (9) and 40s (5). On the warmer side, one high was in the 50s and one high was in the 60s. On the cold side, one high was in the negative 10s (aka negative teens).

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable. In 1976 the high was 40 with a cold low of 7, a 33 degree spread. In 1975 the high was 34 with a low of 28, a six degree spread. In 1973 the high was 38 with a warm low of 32, a six degree spread. In 1972 the high was 35 with a warm low of 31, a four degree spread. In 1971 the high was a warm 45 with a low of 28, a warm day. In 1968 the high was 16 with a low of 5, a cold day. In 1966 the low was a cold 5 degrees. In 1965 the high was 50 with a low of 34, a warm day. In 1964 the high was a warm 47. In 1963 the low was a cold 4 degrees. In 1962 the high was 19 with a low of -4, a cold day.

More recently, we had a large spread of 30 degrees in 1980 (32/2). We also had small spreads of two degrees in 1997 (35/33), four degrees last year (36/32), six degrees in 1993 (18/12), six degrees in 1995 (28/22), six degrees in 2001 (21/15) and six degrees three years ago in 2007 (26/20).

On the cold side, in 1983 the high was the record coldest high of -11 with the record low of -25. Six years later, in 1989, the high was 14 with a low of -6. In 2000 the high was 11 with a low of -2. Four years later, in 2004, the high was 12 with a low of -2. In 1985 the high was 22 with a low of -8. Five years later, in 1990, the high was 16 with a low of 1. Two years later, in 1992, the high was 22 with a low of -3. Other cold lows were 0 in 1984, 2 in 1980 and 6 two years ago. Other cold highs were 18 in 1993 and 20 in 1999. 29 of the last 32 lows (94%) were negative single digits (5), single digits (6), 10s (aka teens)(6), 20s (8) and 30s (5). On the colder side, one low was in the negative 20s. On the warmer side, one low was in the 50s.

Today is a major snow day in O'Hare's history. In 1969, 2.1 inches fell. This was the fourth of four days of measurable snowfall, part of a total of 13.5 inches during the period.

Last year during December, Tom Skilling of the WGN-TV weather center, wrote the following in response to a question about Christmas '65: "Your recall is perfect. Christmas Eve, 1965, was mild and rainy with a high of 51 degrees. In fact it was Chicago's wettest Christmas Eve, with precipitation totaling 2.61 inches, accompanied by thunder and flooding. However, colder air moved in during the evening as a cold front passed through the area and temperatures plunged into the 30s. Rain turned to sleet and then snow with half an inch falling before midnight. At 6 a.m. on Christmas, 2 inches of snow covered the ground at the then official site at Midway Airport, and 1965 was officially declared a white Christmas. The snow cover remained through Dec. 29 then vanished as the mercury climbed to 56 degrees on Dec. 30 and to 60 degrees on New Year's Eve."

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. Sunset is at 16:26 and twilight ends at 16:58. There's a total of 9 hours, 6 minutes of daylight today and 10 hours, 10 minutes between twilights. We are staying at about the same daylight per day. It is the least amount of daylight of the year, at either 9:05 or 9:06. Tomorrow twilight begins at 6:49 and sunrise is at 7:21. The moon is waning gibbous. Illumination was 89% at midnight, will be 86% at noon and 81% at midnight tonight. Moonset is at 9:36 this morning. Moonrise is at 20:36 tonight. Moonset is at 10:06 tomorrow morning. Moonlight time is 13 hours exactly which is 40 minutes shorter than yesterday.

Christmas Eve is today and Christmas Day is tomorrow. -Bernie-