October 29: ORD

Today is October 29th. It's the 302nd day of the year. 63 days remain. It's week 44 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 57 and the normal low is 39. I've calculated the 32-year averages at 58 and 39.

On the warm side, in 2004 the high was 76 with a low of 61. The low was also 61 in 1900. In 1989 the high was 74 with a low of 54. A couple of years later, in 1991, the high was 70 with a low of 55. In 1999 the high was the record high of 78 with a low of 45, a 33 degree spread. The other warm high was 69 in 1979. The record warmest low of 65 was set in 1946 at Midway. 22 of the past 32 highs (69%) were in the: 50s (11) and 60s (11). Highs were in the 50s & 60s for: seven consecutive years from 1981 through 1987 and six consecutive years from 2005 through last year, 2010. Four highs (12%) were in the warm 70s. Six highs (19%) were in the cold: 30s (1) and 40s (5). The last highs in the 40s and 70s came in back to back years (48 in 2003 and 76 in 2004).

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1974 the high was 64 with a warm low of 57, a seven degree spread and warm day. In 1973 the high was 49 with a low of 44, a five degree spread. In 1971 the high was a warm 72 degrees. In 1966 the high was 48 with a cold low of 24, a cool day. In 1965 the high was 55 with a cold low of 22 degrees, a 33 degree spread. In 1964 the low was a cold 27 degrees. In 1963 the high was 57 with a cold low of 27, a 30 degree spread. In 1961 the high was 70 with a low of 55, a warm day. In 1960 the high was 58 with a warm low of 51, a seven degree spread.

More recently, there were large spreads of 33 degrees in 2005 (61/28), 31 degrees in 1984 (61/30) and 30 degrees in 1990 (60/30). There were small spreads of four degrees in 2002 (46/42) and six degrees in 1992 (48/42).

On the cold side, in 1988 the high was 41 with a low of 25. Five years later, in 1993, the high was 39 with a low of 30. In 1980 the high was 47 with a low of 25. The record low of 19 and record coldest high of 29 were set on the same cold day back in 1925, a time when the official readings were taken adjacent to Lake Michigan. 25 of the last 32 lows (78%) were in the: 30s (13) and 40s (12). Lows were in the 30s & 40s for: seven consecutive years from 1981 through 1987 and six consecutive years from 1998 through 2003. Four lows were in the cold 20s. Three lows were in the warm: 50s (2) and 60s (1). The last lows in the 60s and 20s came in back to back years (61 in 2004 and 28 in 2005).

There's an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1988 the high was 41 with a low of 25, overall 15 degrees BELOW normal. Then in 1989 the high was 74 with a low of 54, overall 16 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:53 and sunrise is at 7:22. Sunset is at 17:51 and twilight ends at 18:20. There's a total of 10 hours, 29 minutes of daylight today and 11 hours, 27 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:55 and sunrise is at 7:24. The moon is waxing crescent. Illumination was 9% at midnight, will be 12% at noon and 16% at midnight tonight. Moonrise is at 10:49 this morning. Moonset is at 20:12 tonight. Moonrise is at 11:46 tomorrow morning. Moonlight time is 9 hours, 23 minutes which is nine minutes shorter than yesterday. Moonlight time is at it's least today.

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. Halloween is in two days. Election Day is in ten days. Veterans Day is in 13 days.