October 8: ORD

Today is October 8th. It's the 281st day of the year. 84 days remain. It's week 41 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 46.

On the warm side, in 1997 the high was the record high of 88 with a low of 62. A decade later, in 2007, the high was 87 with a low of 60. The high was also 87 in 1949 (at Midway). The other warm highs were 80 in 2003, 79 last year (in 2010) and 78 in 1993. The other warm lows were 57: in 1984, 1999 and 2004. The record warmest low of 68 occurred in 1939. 28 of the past 32 highs (88%) were in the: 50s (7), 60s (11) and 70s (10). Three highs were in the warm 80s and one was in the cool 40s. The three 80s highs occurred more recently, in 1997, 2003 and 2007. Seven of the ten 70s highs occurred between 1980 and 1993. Then there was a decade long 70s drought between 1994 and 2003.

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1978 the low was a cold 31 degrees. In 1974 the high was 67 with a low of 35, a 32 degree spread. In 1970 the high was 67 with a warm low of 63, a four degree spread. In 1966 the high was a warm 80 with a low of 55, a warm day. In 1963 the high was 75 with a low of 41, a 34 degree spread. In 1961 the high was 76 with a low of 46, a 30 degree spread.

More recently, there were large spreads of 35 degrees in 1982 (75/40), 32 degrees in 2003 (80/48), 31 degrees last year, in 2010 (79/48) and 30 degrees in 1993 (78/48). There were small spreads of six degrees in 1990 (53/47) and seven degrees in 1999 (64/57).

On the cool side, in 2000 the high was 46 with a low of 31. In 1987 the high was 56 with the record low of 27. The other cool highs were 50 in 1996, 53 in 1990, 53 in 2005 and 53 two years ago, in 2009. The record coolest high stands at 41 degrees, which occurred way back in 1895. 20 of the last 32 lows (63%) were in the 40s. Four lows (12%) were in the cold: 20s (1) and 30s (3). Eight lows (25%) were in the warm: 50s (6) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:30 and sunrise is at 6:58. Sunset is at 18:23 and twilight ends at 18:51. There's a total of 11 hours, 25 minutes of daylight today and 12 hours, 21 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:31 and sunrise is at 6:59. The moon is waxing gibbous. Illumination was 87% at midnight, will be 90% at noon and 93% at midnight tonight. Moonset is at 3:42 this morning. Moonrise is at 16:36 this afternoon. Moonset is at 4:42 tomorrow morning. Moonlight time is 11 hours, 6 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 two days.