October 1: ORD

Today is October 1st. It's the 274th day of the year. 91 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 68 and the normal low is 48. I've calculated the 32-year averages at 70 and 47.

On the warm side, in 2002 the high was 82 (our most recent 80s high) with a low of 67. Two years prior, in 2000, the high was 83 with a low of 61. The other warm highs were 81 in 1983 and 80 in 1980. In 1971 the record high of 92 and record warmest low of 71 were established. 25 of the past 32 highs (78%) were in the: 60s (9) and 70s (16). For 14 straight years, from 1986 through 1999, highs were in the 60s & 70s. Four highs were in the warm 80s. Two of these happened between 1980 and 1983 and the other two occurred between 2000 and 2002. There were four highs in the cool 50s. The most recent was 59 two years ago in 2009. Currently, the 80s lead the 50s by a score of 4-3 in the battle of extreme high temperatures.

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1977 the high was 60 with a low of 55, a five degree spread. In 1976 the high was a warm 82 with a low of 46, a 36 degree spread. In 1974 the high was 52 with a low of 33, a cool day. 1974 was also the year of the record low of 32, set at Midway. In 1973 the low was a warm 60 degrees. In 1971 the high was 90 with a low of 71, a hot day. 1971 was the year of the record high of 92 and record warmest low of 71, both set at Midway. In 1969 the high was a warm 85 with a low of 58, a warm day. In 1968 the high was 80 with a low of 61, a warm day. In 1967 the high was 77 with a low of 42, a 35 degree spread. In 1966 the low was a cold 34 degrees. In 1963 the high was a warm 82 with a low of 51, a 31 degree spread. In 1961 the high was 51 with a low of 34, a cool day. 1961 was also the year of the record coolest high of 49, set at Midway.

More recently, there were large spreads of 38 degrees in 1981 (76/38), 36 degrees in 1987 (73/37), 35 degrees in 1983 (81/46), 34 degrees in 1979 (77/43), 33 degrees in 1992 (74/41), 32 degrees in 1984 (65/33) and 30 degrees in 2006 (74/44). There was a small spread of four degrees in 1986 (61/57).

On the cool side, in 2003 the high was 53 with a low of 34. In 1985 the high was 55 with a low of 34. An interesting fact was that highs in the back to back to back years of 1997, 1998 and 1999 were 60, some of the coolest highs of October 1st. Another cold low was 33 in 1984. We had a 15 year reprieve from lows in the 30s from 1988 to 2002, including 12 straight years (1988-1999) of lows in the 40s & 50s. The current seven year streak of lows in the 40s & 50s began in 2004. The record low of 32 was set in 1974 and the record coolest high of 49 occurred in 1961. 25 of the last 32 lows (78%) were in the: 40s (16) and 50s (9). Five lows were in the cold 30s. Four of these five occurred between 1981 and 1987 with a lone one in 2003. Two lows were in the warm 60s, just two years apart (2000 and 2002).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:22 and sunrise is at 6:50. Sunset is at 18:35 and twilight ends at 19:03. There's a total of 11 hours, 45 minutes of daylight today and 12 hours, 41 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:23 and sunrise is at 6:51. The moon is waxing crescent, heading towards first quarter in two days at 22:15. Illumination was 20% at midnight, will be 25% at noon and 30% at midnight tonight. Moonrise is at 12:03 this afternoon. Moonset is at 21:27 tonight. Moonrise is at 13:04 tomorrow afternoon. Moonlight time is 9 hours, 24 minutes which is 15 minutes shorter 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 nine days.