October 11: ORD

Today is October 11th. It's the 284th day of the year. 81 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 64 and 42.

On the warm side, last year, in 2010, the high was 82 (our only 80s high) with a low of 54. In 2003 the high was 78 with a low of 54. In 2008 the high was 79 with a low of 51. The other warm highs were 79 in 1989, 79 in 1995, 76 in 1983 and 76 in 1997. The record high of 87 was set back in 1928. The record warmest low of 66 occurred in 1973. 30 of the past 32 highs (94%) were in the: 50s (10), 60s (12) and 70s (8). One high was in the cold 40s (44 in 2009) and one was in the warm 80s (82 in 2010). So the past couple years have featured highs that were on opposite ends of our high temperature spectrum.

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 a cool 51 degrees. In 1976 the high was 71 with a low of 41, a 30 degree spread. in 1975 the high was 66 with a low of 36, a 30 degree spread. In 1974 the high was a warm 76 with a low of 45, a 31 degree spread. In 1973 the high was 82 with a low of 66, a warm day and year of the record warmest low, also 66 degrees. In 1967 the high was 47 with a low of 30, a cold day. In 1966 the high was 67 with a low of 37, a 30 degree spread. In 1964 the high was 56 with a cold low of 24 (colder than the record low of 27), a cool day. In 1962 the high was 88 with a low of 65, a hot day. That high of 88 was warmer than the record high of 87. In 1961 the high was a warm 77 with a low of 55, a warm day. In 1960 the high was a warm 80 with a low of 53, a warm day. In 1959 the high was a cool 50 degrees.

More recently, there was a large spread of 40 degrees in 1989 (79/39), 33 degrees in 1995 (79/46) and 31 degrees in 1997 (76/45). There was a small spread of five degrees in 2005 (60/55).

On the cool side, two years ago, in 2009, the high was 44 with a low of 29. In 1987 the high was 50 with a low of 29. In 1996 the high was 57 with the record-tying low of 27 (until 2009, our most recent 20s low). The record low of 27 was first set nine decades earlier in 1906. In 1988 the high was 51 with a low of 33. The other cold lows were 32 in 1990 and three years later in 1993. The record coolest high of 41 occurred way back in 1875. 14 of the last 32 lows (44%) were in the 40s. 11 lows (34%) were in the cold: 20s (3) and 30s (8). Seven lows (22%) were in the warm 50s. Five of the seven 50s lows occurred in the last ten years (from 2001 to 2010). The 50s lows before 2001 occurred way before in 1983 and 1984.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:33 and sunrise is at 7:01. Sunset is at 18:18 and twilight ends at 18:46. There's a total of 11 hours, 17 minutes of daylight today and 12 hours, 13 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:34 and sunrise is at 7:02. The moon reaches the full Hunter's moon tonight at 21:06. This moon is also referred to as the Travel or Dying Grass moon. Illumination was 99% at midnight, will be 100% at noon and 100% at midnight tonight. Moonset is at 6:40 this morning. Moonrise is at 17:49 this afternoon. Moonset is at 7:39 tomorrow morning. Moonlight time is 12 hours, 51 minutes which is 34 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 13 days.