December 10: ORD

Today is December 10th. It's the 344th day of the year. 21 days remain. It's week 50 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. ORD has been the official site of record for Chicago since Thursday, January 17, 1980.

According to the National Climatic Data Center (NCDC), the normal high is 36 and the normal low is 22. I've calculated the 32-year averages at 37 and 22.

On the warm side, in 1979 the high was 56 with a low of 31. In 2003 the high was 53 with a low of 29. A year later, in 2004, the high was 45 with a low of 37. Other warm highs were 51 in 1993, 49 in 1991, 48 in 1990 and 48 in 2001. The record high of 62 was set way back in 1879. The record warmest low of 46 occurred back in 1911. Over the last 32 years, 23 highs (72%) were in the: 30s (13) and 40s (10). Three highs were in the warmer 50s. Six highs were in the cold: 10s (a.k.a. teens)(2) and 20s (4).

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 8 with a low of -7, a cold day. That high of 8 is equal to the record coldest high, though unofficially. In 1976 the high was 40 with a low of 7, a 33 degree spread. In 1973 the high was a cold 23 with a low of 12, a cold day. In 1972 the high was 15 with a low of -6, a cold day. In 1971 the high was 57 with a low of 36, a warm day. In 1967 the high was 38 with a low of 36, a two degree spread. In 1965 the high was a warm 51 with a low of 33, a warm day. In 1962 the high was 18 with a low of 4, a cold day. In 1958 the high was 12 with a low of -8, a cold day. That low of -8 is equal to the record low, though unofficially.

More recently, there were no other large spreads of 30 degrees or more. There were small spreads of three degrees in 1997 (36/33), four degrees in 1992 (34/30), seven degrees in 1985 (37/30) and seven degrees in 2007 (32/25).

On the cold side, in 1978 the high was 21 with a low of -10, a 31 degree spread. Last year the high was 13 with a low of 0. In 1995 the high was 14 with a low of 0. In 1986 the high was 20 with a low of 9. Other cold lows were 8 in 1988 and 9 in 1983. The record low of -8 was set in 1978 at Midway. The low of -8 also occurred back in 1919. The record coldest high of 8 occurred back in 1919. 22 of the last 32 lows (69%) were: 20s (12) and 30s (10). Ten lows were in the cold: negative 10s (1), 0s (5) and 10s (4). There's been an absence of lows in the negative 0s.

Three recent days (December 5, 6 and 8) have each been the third coldest of the past 33 years. In other words, they were in the top 9% of cold days for each date. December 7 and yesterday, December 9 were the fourth coldest of their dates, in the top 12% of cold days for each.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 6:39 and sunrise was at 7:11. Sunset was at 16:21 and twilight ended at 16:53. There's a total of 9 hours, 10 minutes of daylight today and 10 hours, 14 minutes between twilights. We are losing a minute of daylight per day. Tomorrow twilight begins at 6:40 and sunrise is at 7:12. The moon is waxing crescent. Illumination was 20% at midnight, will be 24% at noon and 29% at midnight tonight. Moonrise was at 10:35 this morning. Moonset is at 21:30 tonight. Moonrise is at 11:00 tomorrow morning. Moonlight time is 10 hours, 55 minutes which is 34 minutes longer than yesterday.

Bill of Rights Day is in five days. Christmas Eve is in 14 days. -Bernie-