December 2: ORD

Today is December 2nd. It's the 336th day of the year. 29 days remain. It's week 48 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 40 and the normal low is 25. I've calculated the 33-year averages at 41 and 26.

On the warm side, in 1982 the high was the record high of 71 (O'Hare's only 70s high) with the record warmest low of 58 (O'Hare's only 50s low). In 1998 the high was 61 (our most recent 60s high) with a low of 49. The next year, 1999, the high was 58 with a low of 41. Five years before, in 1994, the high was 54 with a low of 38. The other warm highs were 57 in 1995 and 52 in 2001 (our most recent 50s high). 25 of the past 33 highs (76%) were in the: 30s (15) and 40s (10). There were eight consecutive 30s & 40s highs from 1986 through 1993. Six highs were in the warm: 50s (4), 60s (1) and 70s (1). Pre-1978, the 60s highs were 64 in both 1962 and 1973. Two highs were in the cold 20s. There was a high of 16 in 1966.

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 21 with a low of 2, a cold day. Ten of the first 13 days of December 1976 had single-digit lows. The other three days were in the 10s. In 1973 the high was a warm 64 with a low of 36, a warm day. Also in 1973, the high on the 3rd was 62. In 1972 the high was 49 with a low of 16, a 33 degree spread. In 1970 the high was a warm 56 with a low of 35, a warm day. In 1968 the high was 41 with a low of 35, a six degree spread. In 1967 the high was 38 with a low of 34, a four degree spread. In 1966 the high was 16 with a low of 2, a cold day. In 1963 the low was a cold 10 degrees. In 1962 the high was a warm 64 with a low of 25, a 39 degree spread and warm day. In 1961 the high was a warm 54 degrees.

More recently, there was a large spread of 32 degrees in 1995 (57/25). There were small spreads of five degrees in 1987 (33/28), seven degrees in 1986 (42/35), seven degrees in 1997 (40/33) and seven degrees in 1991 (34/27).

On the cold side, in 1985 the high was 22 with a low of 7. Two decades later, in 2005, the high was 24 with a low of 13. The other cold lows were 11 in 1980, 12 in 1979 and 12 in 2006. The record low of -1 and record coldest high of 14 were set on the same cold day back in 1942 at Midway. The record low of -1 was originally set way back in 1893, at a time when the official observations were taken adjacent to Lake Michigan. 18 of the last 33 lows (55%) were in the 20s. Seven lows (21%) were in the cold: 0s (1) and 10s (6). Pre-1978, there were lows of 2 degrees in both 1966 and 1976. The low was 10 in 1963 and 16 in 1972. Eight lows (24%) were in the warm: 30s (5), 40s (2) and 50s (1).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:32 and sunrise is at 7:03. Sunset is at 16:22 and twilight ends at 16:53. There's a total of 9 hours, 19 minutes of daylight today and 10 hours, 21 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 6:33 and sunrise is at 7:04. The moon reaches first quarter at 3:52. Illumination was 49% at midnight, will be 53% at noon and 58% at midnight tonight. Moonrise is at 12:07 this afternoon. Moonset is at 0:25 tomorrow morning. Moonrise is at 12:31 tomorrow afternoon. Moonlight time is 11 hours, 53 minutes which is 10 minutes longer than yesterday.

Winter began yesterday and runs for 102 days through March 11. 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 five days. Bill of Rights Day is in 13 days.