October 7: ORD

Today is October 7th. It's the 280th day of the year. 85 days remain. It's week 40 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 66 and the normal low is 45. I've calculated the 32-year averages at 66 and 44.

On the warm side, in 2007 the high was the record high of 87 with the record warmest low of 67. The former record high was 86 in 1947. The former record warmest low was 66 in 1914. A decade earlier, in 1997, the high was 84 with a low of 63. In 1993 the high was 81 with a low of 58. The next year, 1994, the high was 75 with a low of 61. The other warm high was 80 in 2003. The other warm low was 60 in 1984. 26 of the past 32 highs (81%) were in the: 50s (7), 60s (11) and 70s (8). Four highs in the warm 80s and two were in the cold 40s. Both 40s highs were 49 degrees (in 1987 and 2000).

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1978 the high was a cool 54 degrees. In 1977 the high was a cool 53 degrees. In 1976 the high was a cool 50 degrees. In 1975 the high was 76 with a low of 43, a 33 degree spread. In 1974 the high was 54 with a low of 32, a cool day. In 1973 the low was a warm 58 degrees. In 1970 the high was 79 with a low of 63, a warm day. In 1966 the high was a warm 78 with a low of 47, a 31 degree spread. In 1964 the high was 68 with a cold low of 24, a 44 degree spread. That low of 24 is colder than the record low. In 1963 the high was a warm 81 with a low of 49, a 32 degree spread. In 1962 the low was a warm 60 degrees. In 1959 the high was 61 with a warm low of 57, a mere four degree spread.

More recently, there were large spreads of 39 degrees in 2003 (80/41), 35 degrees in 1985 (71/36), 33 degrees in 2004 (76/43), 33 degrees in 1980 (74/41) and 32 degrees in 1983 (77/45). There were small spreads of five degrees in 1984 (65/60), seven degrees in 1995 (53/46) and seven degrees three years ago, in 2008 (63/56).

On the cool side, in 2000 the high was 49 with a low of 30. In 1987 the high was also 49 with a low of 30. In 2001 the high was 52 with the record low of 29. The former record low of 30 occurred in both 1987 and 2000. The other cold low was 33 in 1991. The other cool highs were 53 in 1995 and 54 in 2005. The record coolest high stands at 47, which occurred way back in 1896. 23 of the last 32 lows (72%) were in the: 30s (9) and 40s (14). One low was in the cold 20s. Eight lows were in the warm: 50s (4) and 60s (4). Interestingly, the last 30s low was 11 years ago in 2000 (30 degrees) and the lone 20s low (the record low of 29) occurred a year later in 2001. Eight of the nine 30s lows (89%) occurred between 1979 and 1991.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:29 and sunrise is at 6:57. Sunset is at 18:25 and twilight ends at 18:53. There's a total of 11 hours, 28 minutes of daylight today and 12 hours, 24 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:30 and sunrise is at 6:58. The moon is waxing gibbous. Illumination was 80% at midnight, will be 84% at noon and 87% at midnight tonight. Moonset was at 2:41 this morning. Moonrise is at 16:11 this afternoon. Moonset is at 3:42 tomorrow morning. Moonlight time is 10 hours, 30 minutes which is 36 minutes longer than yesterday.

Warm Fall began September 22 and runs for 41 days through November 1. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 30s and 40s occur infrequently. Columbus Day is in three days.