October 6: ORD

Today is October 6th. It's the 279th day of the year. 86 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 66 and the normal low is 46. I've calculated the 32-year averages at 67 and 45.

On the warm side, in 2007 the high was 87 with a low of 69. That high of 87 is our co-warmest high and most recent 80s high. The low of 69 is our most recent 60s low and warmest low. In 1982 the high was 87 (the other co-warmest high) with a low of 61. In 1990 the high was 84 with a low of 60. In 1997 the high was 84 with a low of 56. The record high of 94 was set in 1963. The record warmest low of 70 occurred way back in 1879. 27 of the past 32 highs (84%) were in the: 50s (9), 60s (9) and 70s (9). Four highs were in the warm 80s and one was in the cold 40s (48 in 2000).

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1970 the high was 79 with a low of 60, a warm day. In 1968 the high was 52 with a low of 48, a four degree spread. In 1966 the high was 67 with a cold low of 28, a 39 degree spread. That low of 28 is equal to the record low, set in 1952 at Midway. In 1964 the high was 52 with a low of 25, a cold day. That low of 25 is colder than the record low of 28, set in 1952 at Midway. In 1963 the high was 91 with a low of 58, a 33 degree spread and hot day. 1963 was the year of the record high of 94, set at Midway. In 1959 the low was a warm 58 degrees.

More recently, there were large spreads of 34 degrees in 1992 (70/36), 34 degrees in 1993 (78/44), 33 degrees in 1980 (70/37) and 32 degrees last year, in 2010 (78/46). There were no small spreads of up to seven degrees.

On the cool side, in 2001 the high was 50 with a low of 30. A year earlier, in 2000, the high was 48 (our only 40s high) with a low of 34. In 1988 the high was 56 with a low of 30. In 1991 the high was 53 with a low of 35. The other cold low was 32 in 1985. The other cool high was 54 in 1987. The record low of 28 and record coolest high of 46 were set on the same cold day in 1952 at Midway. 29 of the last 32 lows (91%) were in the: 30s (11), 40s (11) and 50s (7). Three lows were in the warm 60s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:28 and sunrise is at 6:56. Sunset is at 18:27 and twilight ends at 18:55. There's a total of 11 hours, 31 minutes of daylight today and 12 hours, 27 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:29 and sunrise is at 6:57. The moon is waxing gibbous. Illumination was 71% at midnight, will be 76% at noon and 80% at midnight tonight. Moonset was at 1:38 this morning. Moonrise is at 15:44 this afternoon. Moonset is at 2:41 tomorrow morning. Moonlight time is 9 hours, 54 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. Columbus Day is in four days.