October 2: ORD

Today is October 2nd. It's the 275th day of the year. 90 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 47. I've calculated the 32-year averages at 68 and 46.

On the warm side, in 1991 the high was 80 with a low of 59. In 2005 the high was 84 with a low of 54, a 30 degree spread. The next year, in 2006, the high was 77 with a low of 61 (our most recent 60s low). In 1983 the high was 88 (our warmest high) with a low of 49, a 39 degree spread. In 2000 the high was 81 with a low of 56. The other warm highs were 81 in 1982 and 80 in 2001. The other warm lows were 60 degrees in 1986 and 2002. In 1971 the record high of 91 and record warmest low of 69 were established at Midway. Over the past 32 years, the four categories of highs have been almost equal: 50s (9 for 28%), 60s (10 for 31%), 70s (7 for 22%) and 80s (6 for 19%). Interestingly, although the 60s are most represented, only one 60 degree high has occurred in the past 14 years (1997-2010). This was 61 three years ago in 2008. Of the 13 other highs, six were 50s, four were 70s and three were 80s. The 60s were most in vogue from 1984 to 1989 when five of those six years had one.

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1976 the high was a warm 80 with a low of 49, a 31 degree spread. In 1974 the high was 50 with a low of 27, a cool day. That low of 27 was colder than the record low of 28 which was set this same year at Midway. In 1972 the high was 78 with a low of 46, a 32 degree spread. In 1971 the high was 89 with a low of 69, a hot day. 1971 was the year of the record high of 91 and record warmest low of 69, both set at Midway. In 1969 the low was a warm 59 degrees. In 1967 the high was 84 with a low of 61, a warm day. In 1966 the high was 69 with a cold low of 33, a 36 degree spread. In 1963 the high was a warm 82 degrees. In 1962 the low was a warm 60 degrees. In 1961 the high was 52 with a low of 30, a cool day.

More recently, there were large spreads of 37 degrees in 1997 (79/42), 34 degrees in 1990 (73/39), 32 degrees in 1982 (81/49), 32 degrees in 2001 (80/48), 31 degrees in 1984 (68/37) and 30 degrees in 1992 (78/48). There was a small spread of seven degrees in 1986 (67/60).

On the cool side, in 2003 the high was 53 with a low of 31, our coldest low. In 1981 the high was 52 (our coolest high) with a low of 32. In 1993 the high was 55 with a low of 33. In 1999 the high was 55 with a low of 36. In 1987 the high was 58 with a low of 33. The other cold low was 34 in 1985. The other cool high was 56 two years ago in 2009. The record low of 28 was set in 1974 and the record coolest high of 48 occurred way back in 1888, a time when the official readings were taken adjacent to Lake Michigan. 13 of the last 32 lows (41%) were in the 40s. Nine lows (28%) were in the cold 30s. Ten lows (31%) were in the warm: 50s (7) and 60s (3). The tallies of lows over the last nine years has been fairly even: two 30s, three 40s, two 50s and two 60s. Our most recent 30s low was 37 in 2004. There was a 15 year absence of lows in the 60s between the low of 60 in 1986 to the low of 60 in 2002.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:23 and sunrise is at 6:51. Sunset is at 18:34 and twilight ends at 19:01. There's a total of 11 hours, 43 minutes of daylight today and 12 hours, 38 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:24 and sunrise is at 6:52. The moon is waxing crescent, heading towards first quarter tomorrow at 22:15. Illumination was 30% at midnight, will be 35% at noon and 41% at midnight tonight. Moonrise is at 13:04 this afternoon. Moonset is at 22:26 tonight. Moonrise is at 13:56 tomorrow afternoon. Moonlight time is 9 hours, 22 minutes which is two 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 eight days.