October 10: ORD

Today is October 10th. It's the 283rd day of the year. 82 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 65 and the normal low is 44. I've calculated the 32-year averages at 62 and 43.

On the warm side, last year, in 2010, the high was 84 with a low of 57. Only 1973 (see below) was warmer than 2010 at O'Hare. In 1999 the high was 79 with a low of 53. The other warm high was 77 in 2003. The record high of 86 was set in 1962 at Midway. The other warm low was 56 in 1984. The record warmest low of 68 occurred way back in 1879, a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 32 highs (69%) were in the: 50s (8) and 60s (14). Six highs (19%) were in the warm: 70s (5) and 80s (1). All of the 70s & 80s occurred between 1995 and 2010. Four highs (12%) were in the cold 40s (the two highs of 48: in 1990 and two years ago in 2009).

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1978 the high was 62 with a low of 55, a seven degree spread. In 1974 the high was 70 with a low of 38, a 32 degree spread. In 1973 the high was 81 with a low of 65, a warm day. In 1967 the high was a cool 51 with a low of 36, a cool day. In 1964 the high was 48 with a low of 20 (cooler than the record low and year of the record low), a cold day. In 1963 the high was a warm 82 with a low of 50, a 32 degree spread and warm day. In 1962 the high was a hot 87 with a low of 43, a 44 degree spread. 1962 was the year of the record high (see above). In 1961 the high was 80 with a low of 60, a warm day. In 1960 the high was a warm 79 with a low of 47, a 32 degree spread.

More recently, there was a large spread of 30 degrees three years ago, in 2008 (72/42). There were small spreads of six degrees in 2006 (58/52) and seven degrees in 2007 (54/47).

On the cool side, two years ago, in 2009, the high was 48 with a low of 31. In 1996 the high was 50 with a low of 31. In 1990 the high was 48 with a low of 34. In 1993 the high was 53 with a low of 30. In 1987 the high was 48 with a low of 37. The other cool or cold high was 47 in 1985. The record low of 27 was set in 1964 at Midway. The record coldest high of 39 occurred way back in 1906, a time when the official readings were taken adjacent to Lake Michigan. 25 of the last 32 lows (78%) were in the: 30s (12) and 40s (13). Seven lows were in the warm 50s. Six of those seven 50s lows (86%) occurred between 1999 and 2010.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:32 and sunrise is at 7:00. Sunset is at 18:20 and twilight ends at 18:48. There's a total of 11 hours, 20 minutes of daylight today and 12 hours, 16 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:33 and sunrise is at 7:01. The moon is waxing gibbous and reaches the full Hunter's moon tomorrow night at 21:06. This moon is also referred to as the Travel or Dying Grass moon. Illumination was 97% at midnight, will be 98% at noon and 99% at midnight tonight. Moonset is at 5:41 this morning. Moonrise is at 17:24 this afternoon. Moonset is at 6:40 tomorrow morning. Moonlight time is 12 hours, 17 minutes which is 35 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 today.