December 25: ORD

Today is December 25th. It's the 359th day of the year. Six 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 17. The 32-year averages are 29 and 13.

On the warm side, in 1982 the high was the record high of 64 with a low of 36. In 1994 the high was 52 with a low of 24. Other warm lows were 33 in 2005, 30 in 2006, 29 in 1987 and 28 in 1979. The record warmest low of 46 occurred in 1936. 19 of the last 32 highs (59%) were: 20s (7) and 30s (12). On the warmer side, five highs (16%) were: 40s (3), 50s (1) and 60s (1). On the colder side, eight highs (25%) were: negative single digits (1), single digits (2) and 10s (aka teens)(5).

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable. In 1977 the high was 14 with a low of -2, a cold day. In 1975 the high was 36 with a warm low of 31, a five degree spread. In 1973 the high was 40 with a warm low of 37, a three degree spread and warm day. In 1972 the high was 35 with a warm low of 31, a four degree spread. In 1971 the high was 45 with a low of 30, a warm day. In 1969 the high was 28 with a low of 21, a seven degree spread. In 1968 the high was 18 with a low of 0, a cold day. In 1964 the high was 27 with a low of 23, a four degree spread.

More recently, we had small spreads of three degrees in 2005 (36/33), six degrees in 1986 (32/26), six degrees in 2002 (29/23), seven degrees in 1987 (36/29) and seven degrees in 2006 (37/30).

On the cold side, in 1983 the high was the record coldest high of -5 with the record low of -17. Two years later, in 1985, the high was 2 with a low of -11. Five years earlier, in 1980, the high was 17 with a low of -8. Two decades later, in 2000, the high was 17 with a low of -7. Four years before that, in 1996, the high was 9 with a low of 1. In 1984 the high was 19 with a low of -3. In 1993 the high was 18 with a low of 5. Two years ago the high was 24 with a low of 0. In 1990 the high was 28 with a low of -1. Another cold high was 19 in 2004. 19 of the last 32 lows (59%) were: 10s (11) and 20s (8). On the colder side, ten lows (31%) were: negative 10s (aka negative teens)(2), negative single digits (4) and single digits (4). On the warmer side, three lows (9%) were in the 30s. Through Winter 2010-11, this is the average sixth coldest day of the year.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:49 and sunrise is at 7:21. Sunset is at 16:26 and twilight ends at 16:58. There's a total of 9 hours, 5 minutes of daylight today and 10 hours, 9 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 81% at midnight, will be 77% at noon and 72% at midnight tonight. Moonset is at 10:06 this morning. Moonrise is at 21:50 tonight. Moonset is at 10:34 tomorrow morning. Moonlight time is 12 hours, 16 minutes which is 44 minutes shorter than yesterday.

Today is not a major snow day in O'Hare's history. The next one is in a couple of days and it occurred way back in 1894! Christmas Day is today, New Year's Eve is in six days and New Year's Day is in seven days. -Bernie-