December 3: ORD

Today is December 3rd. It's the 337th day of the year. 28 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. Before this, the official site was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 39 and the normal low is 25. I've calculated the 33-year averages at 39 and 24.

On the warm side, in 1998 the high was 67 (our most recent 60s high) with the record warmest low of 54. In 1982 the high was 62 with a low of 47. In 1999 the high was 57 with a low of 48. Two years later, in 2001, the high was 56 (our most recent 50s high) with a low of 41 (our most recent 40s low). In 1994 the high was 54 with a low of 42. The next year, 1995, the high was 57 with a low of 35. The other warm high was 54 in 1988. The record high of 71 was set in 1970 at Midway. 16 of the past 33 highs (49%) were in the 30s. 11 highs (33%) were in the warm: 40s (4), 50s (5) and 60s (2). The 60s highs, pre-1978, were 67 in 1970, 62 in 1961 and 62 in 1973. Our most recent 40s high was 43 in 1993. Six highs (18%) were in the cold: 10s (1) and 20s (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 a cold 27 with a low of 14, a cold day. In 1976 the high was 21 with a low of 9, a cold day. In 1973 the high was 62 with a low of 44, a warm day. In 1970 the high was 67 with a low of 40, a warm day and year of the record high of 71 at Midway. In 1966 the high was 23 with a low of 2, a cold day. In 1964 the high was 34 with a low of 29, a five degree spread. In 1963 the high was 23 with a low of 8, a cold day. In 1962 the high was a warm 59 with a low of 33, a warm day. In 1961 the high was a warm 62 with a low of 33, a warm day. In 1958 the high was 37 with a low of 31, a six degree spread.

More recently, there were no large spreads. There were small spreads of three degrees in 1997 (38/35) and six degrees in 1986 (35/29).

On the cold side, in 2006 the high was the record coldest high of 15 with a low of 8, a seven degree spread. The former record coldest high of 16 occurred in 1942. Two decades and a year earlier, in 1985, the high was 24 with a low of 5. In 2002 the high was 24 with a low of 14. In 1989 the high was 25 with a low of 15. In 1980 the high was 30 with a low of 10. The other cold low was 13 in 1991. The other cold high was 27 in 1984. The record low of -5 was set in 1940, at a time when the official readings were taken adjacent to Lake Michigan. 23 of the last 33 lows (70%) were in the: 10s (10) and 20s (13). Two lows (6%) were in the cold 0s. The 0s lows, prior to 1978, are 2 in 1966, 8 in 1963 and 9 in 1976. Eight lows (24%) were in the warm: 30s (3), 40s (4) and 50s (1). Our most recent 30s low was 35 in 1997.

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. First instance: In 1988 the high was 54 with a low of 31, overall 10.5 degrees ABOVE normal. Then in 1989 the high was 25 with a low of 15, overall 12 degrees BELOW normal. Second instance: In 2001 the high was 56 with a low of 41, overall 16.5 degrees ABOVE normal. Then in 2002 the high was 24 with a low of 14, overall 13 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:33 and sunrise is at 7:04. Sunset is at 16:22 and twilight ends at 16:53. There's a total of 9 hours, 18 minutes of daylight today and 10 hours, 20 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 6:34 and sunrise is at 7:05. The moon is waxing gibbous, having reached first quarter yesterday at 3:52. Illumination was 58% at midnight, will be 63% at noon and 67% at midnight tonight. Moonset is at 0:25 this morning. Moonrise is at 12:31 this afternoon. Moonset is at 1:25 tomorrow morning. Moonlight time is 11 hours, 54 minutes which is one minute longer than yesterday.

Winter began December 1st and runs for 102 days through March 11th. High temperatures in this period are usually in the 20s and 30s. Highs in the 40s and 50s occur infrequently. Pearl Harbor Day is in four days. Bill of Rights Day is in 12 days.