November 11: ORD

Today is November 11th. It's the 315th day of the year. 50 days remain. It's week 45 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. Before this, the official site was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 51 and the normal low is 35. I've calculated the 33-year averages at 47 and 32.

On the warm side, last year, in 2010, the high was 67 with a low of 46. In 1982 the high was 61 with a low of 49. The record high of 74 was last set in 1964 (at Midway) and originally in 1911. The record warmest low of 62 was set way back in 1882, a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 33 highs (67%) were in the: 40s (10) and 50s (12). Seven consecutive highs, 1998 through 2004, were in the 40s & 50s. Three highs (9%) were in the warm 60s. The other 60s high was 60 in 2005. Eight highs (24%) were in the cold 30s. Some of the coldest years were 1983 through 1986 when 3 of the 4 highs were in the 30s. The other high was 40 in 1985, just above the 30s. Then in three straight years, from 1995-1997, highs were in the 30s. There was only one 70s high in O'Hare's history on November 11. That was 73 in 1964.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1977 the high was a cold 39 degrees. In 1976 the high was 33 with a low of 19, a cold day. In 1972 the high was 45 with a low of 41, a four degree spread. In 1969 the high was 49 with a low of 43, a six degree spread. In 1967 the high was 59 with a warm low of 50, a warm day. In 1964 the high was 73 with a low of 57, a warm day and year of the record high of 74 at Midway. In 1961 the high was a warm 65 with a low of 33, a 32 degree spread.

More recently, there were no large spreads. There were small spreads of four degrees in 1985 (40/36), five degrees in 2002 (41/36), six degrees in 1991 (38/32) and seven degrees in 2006 (41/34).

On the cold side, in 1986 the high was 31 with a low of 20. In 1995 the high was 36 with a low of 17. A year later, in 1996, the high was 32 with a low of 22. A year after that, in 1997, the high was 33 with a low of 25. In 1979 the high was 40 with a low of 18. In 1984 the high was 35 with a low of 25. A year earlier, in 1983, the high was 36 with a low of 24. Three years ago, in 2008, the high was 38 with a low of 23. The other cold high was 38 in 1991. The record low of 15 was set in 1950 and the record coldest high of 28 occurred way back in 1894. 26 of the last 32 lows (79%) were in the: 20s (10) and 30s (16). There were consecutive lows in the 20s & 30s: six years from 1983 through 1988 and seven years from 1996 through 2002. Two lows (6%) were in the cold 10s. Five lows (15%) were in the warm 40s. There's been just two 50s lows in O'Hare's history on 11/11: 57 in 1964 and 50 in 1967.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1982 the high was 61 with a low of 49, overall 12 degrees ABOVE normal. Then in 1983 the high was 36 with a low of 24, overall 13 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:09 and sunrise is at 6:39. Sunset is at 16:36 and twilight ends at 17:06. There's a total of 9 hours, 57 minutes of daylight today and 10 hours, 57 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:10 and sunrise is at 6:40. The moon is waning gibbous, having passed full yesterday at 14:16 as the full Beaver (aka Frost) moon. Illumination was 100% at midnight, will be 99% at noon and 98% at midnight tonight. Moonset is at 7:29 this morning. Moonrise is at 17:03 this afternoon. Moonset is at 8:24 tomorrow morning. Moonlight time is 14 hours, 26 minutes which is 19 minutes longer than yesterday.

Cool Fall began November 2 and runs for 29 days through November 30. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 10s and 20s occur infrequently. Veterans Day is today. Thanksgiving is in 13 days.