November 6: ORD

Today is November 6th. It's the 310th day of the year. 55 days remain. It's week 45 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 53 and the normal low is 37. I've calculated the 33-year averages at 51 and 34.

On the warm side, three years ago, in 2008, the high was 65 with a low of 45. In 1996 the high was 63 with a low of 45. In 2004 the high was 65 with a low of 42. Our warmest high (of the last 33 years) was 68 in 1980 but since the low was 28, the day was just three degrees above normal. However, that spread of 40 degrees is remarkable. The record high of 75 was set in 1975 at Midway. The record warmest low of 63 occurred in 1924, a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 33 highs (67%) were in the: 40s (11) and 50s (11). Seven consecutive highs in the 40s & 50s occurred from 1981 through 1987. Seven highs (21%) were in the warm 60s. Six of the 60s highs (86% of them) occurred in a 14 year span from 1996 through 2009. Included were 60s highs in the back-to-back years of 2004/2005 and 2008/2009. Four highs (12%) were in the cold 30s. All of the 30s highs occurred in a six year span from 1988 through 1993, including three consecutive from 1991 through 1993.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1977 the high was 59 with a warm low of 52, a spread of seven degrees. In 1975 the high was 75 with a low of 57, a warm day and year of the record high of 75, set at Midway. In 1973 the high was 41 with a low of 20, a cold day. In 1971 the low was a cold 24 degrees. In 1969 the high was 60 with a low of 30, a 30 degree spread. In 1968 the high was 48 with a low of 45, a three degree spread. In 1965 the high was 64 with a low of 55, a warm day. In 1961 the high was 40 with a low of 23, a cold day. In 1960 the high was a cold 41 degrees. In 1959 the high was 30 with a low of 24, a six degree spread, cold day and year of the record coldest high of 29 at Midway.

More recently, the only large spread (30 degrees or more) was 40 degrees in 1980 (68/28). There were small spreads of four degrees in 1997 (47/43), seven degrees in 1989 (49/42) and seven degrees in 2002 (43/36).

On the cold side, in 1993 the high was 32 with a low of 20. A couple of years earlier, in 1991, the high was 36 with the record low of 19. Three years earlier, in 1988, the high was 36 with a low of 31, a five degree spread. Four years later, in 1992, the high was 37 with a low of 31, a six degree spread. The other cold lows were 23 in 1984, 25 in 1982 and 25 last year, in 2010. The record coldest high of 29 occurred in 1959. 18 of the last 33 lows (55%) were in the 30s. Seven lows (21%) were in the cold: 10s (1) and 20s (6). Five of the 20s lows (83% of them) occurred in a 14 year span from 1980 through 1993. Eight lows (24%) were in the warm 40s. Seven of the 40s lows (88% of them) occurred in a 13 year span from 1996 through 2008, including two in a row (1996/1997) and three in a row (2004-6).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:03 and sunrise is at 6:32. Sunset is at 16:41 and twilight ends at 17:11. There's a total of 10 hours, 9 minutes of daylight today and 11 hours, 8 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:04 and sunrise is at 6:34. The moon is waxing gibbous. Illumination was 82% at midnight, will be 86% at noon and 89% at midnight tonight. Moonset is at 2:34 this morning. Moonrise is at 14:28 this afternoon. Moonset is at 3:33 tomorrow morning. Moonlight time is 12 hours, 6 minutes which is 35 minutes longer than yesterday.

Cool Fall began November 2 and runs for 29 days through November 30. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 10s and 20s occur infrequently. Election Day is in two days. Veterans Day is in five days. Thanksgiving is in 18 days.