October 13: ORD

Today is October 13th. It's the 286th day of the year. 79 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 64 and the normal low is 44. I've calculated the 32-year averages at 63 and 42.

On the warm side, three years ago, in 2008, the high was 77 with a low of 61. In 1995 the high was 83 with a low of 52, a 31 degree spread. A year later, in 1996, the high was 77 with a low of 56. In 2000 the high was 78 with a low of 54. The other warm high was 81 in 1989. Those two 80s highs were the only 80s highs of the past 32 years, part of just five 80s highs that O'Hare has had on October 13th. The other warm lows were 60 in 1984 and 55 in 2001. The record high of 88 was set in 1975 at Midway. The record warmest low of 67 occurred back in 1920, a time when the official readings were taken adjacent to Lake Michigan. 28 of the past 32 highs (88%) were in the: 50s (11), 60s (10) and 70s (7). Two highs were in the warm 80s and two were in the cool 40s.

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 61 with a cold low of 31, a 30 degree spread. In 1975 the high was 87 with a low of 64, a hot day. 1975 was the year of the record high of 88 at Midway. In 1970 the low was a warm 56 degrees. In 1968 the high was 80 with a low of 59, a warm day. In 1964 the high was 68 with a cold low of 30, a 38 degree spread. In 1963 the high was 72 with a cold low of 32, a 40 degree spread. In 1962 the high was a warm 81 with a low of 47, a 34 degree spread. In 1960 the high was 79 with a low of 61, a warm day. In 1959 the high was a cool 47 degrees with a low of 38, a cool day.

More recently, there were large spreads of 40 degrees in 1989 (81/41), 32 degrees in 1987 (65/33), 32 degrees in 2003 (73/41), 30 degrees in 1997 (74/44) and 30 degrees in 1980 (58/28). There were small spreads of six degrees in 1984 (66/60) and seven degrees in 1986 (47/40).

On the cool side, in 1988 the high was 53 with the record low of 25. Two years ago, in 2009, the high was 47 with a low of 34. In 1993 the high was 53 with a low of 28. In 2006 the high was 50 with a low of 32. In 2002 the high was 50 with a low of 33. The other cool highs were 47 in 1986 and 52 in 1979. The other cold low was 28 in 1980. The record coolest high of 45 occurred back in 1909. 22 of the last 32 lows (69%) were in the: 30s (8) and 40s (14). Three lows (9%) were in the cold 20s. Seven lows (22%) were in the warm: 50s (5) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:35 and sunrise is at 7:03. Sunset is at 18:15 and twilight ends at 18:43. There's a total of 11 hours, 12 minutes of daylight today and 12 hours, 8 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:36 and sunrise is at 7:05. The moon is waning gibbous, having reached the full Hunter's moon two nights ago at 21:06. This moon is also referred to as the Travel or Dying Grass moon. Illumination was 99% at midnight, will be 97% at noon and 96% at midnight tonight. Moonset is at 8:38 this morning. Moonrise is at 18:47 tonight. Moonset is at 9:37 tomorrow morning. Moonlight time is 13 hours, 51 minutes which is 29 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. United Nations Day is in 11 days.