December 7: ORD

Today is December 7th. It's the 341st day of the year. 24 days remain. It's week 49 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 37 and the normal low is 23. I've calculated the 32-year averages at 36 and 25.

On the warm side, in 1980 the high was 59 with the record warmest low of 45. In 2004 the high was 50 with a low of 41. In 1981 the high was 52 with a low of 38. A decade later, in 1991, the high was 49 with a low of 39. Another warm low was 35 in 2001. The record high of 64 was set in 1916. Over the last 32 years, 23 highs (72%) were in the: 30s (13) and 40s (10). The most recent 40s high was 41 in 2003. Three highs were in the warmer 50s. Six highs was in the cooler: 10s (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 15 with a low of -1, a cold day. In 1976 the high was 19 with a low of 3, a cold day. In 1974 the high was 40 with a warm low of 35, a five degree spread. In 1972 the high was 22 with a low of -2, a cold day. In 1971 the high was 44 with a warm low of 40, a four degree spread and warm day. In 1969 the high was 37 with a low of 33, a four degree spread. In 1967 the high was 51 with a low of 39, a warm day. In 1966 the high was 46 with a warm low of 40, a six degree spread. In 1963 the high was a warm 56 degrees with a low of 22, a 34 degree spread. In 1958 the high was 14 with a low of 5, a cold day.

More recently, there were no large spreads of 30 degrees or more. There were small spreads of two degrees in 1997 (31/29), four degrees in 1982 (36/32), four degrees in 1986 (38/34), five degrees last year (31/26), six degrees in 2007 (30/24) and seven degrees in 1992 (30/23).

On the cold side, in 2005 the high was 15 with a low of 0. Three years later and two years ago (2008), the high was 20 with a low of 4. Two years earlier, in 2006, the high was 17 with a low of 9. In 1984 the high was 27 with a low of 7. In 1989 the high was 23 with a low of 12. The record low of -6 and record coldest high of 6 were set on the same day way back in 1882. 14 of the last 32 lows (44%) were 20s. Eight lows (25%) were in the cold: 0s (4) and 10s (4). Our most recent 10s low was 18 in 1995. Ten lows (31%) were in the warmer: 30s (8) and 40s (2). Our most recent 30s low was 35 in 2001.

The past two days (December 5 & 6) 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.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:37 and sunrise is at 7:08. Sunset is at 16:21 and twilight ends at 16:53. There's a total of 9 hours, 13 minutes of daylight today and 10 hours, 16 minutes between twilights. We are losing a minute of daylight per day. Tomorrow twilight begins at 6:38 and sunrise is at 7:09. The moon became new two days ago at 11:36 and is waxing crescent. Illumination was 3% at midnight, will be 5% at noon and 7% at midnight tonight. Moonrise is at 8:55 this morning. Moonset is at 18:20 this afternoon. Moonrise is at 9:35 tomorrow morning. Moonlight time is 9 hours, 25 minutes which is 16 minutes longer than yesterday.

Pearl Harbor Day is today. Bill of Rights Day is in eight days. -Bernie-