November 10: ORD

Today is November 10th. It's the 315th day of the year. 51 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. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. 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 34-year averages at 50 and 33.

On the warm side, in 1999 (O'Hare's warmest November 10th) the high was 69 (O'Hare's warmest high of the date) with a low of 47 (O'Hare's co-warmest low of the date). Two years ago, in 2010 (O'Hare's second warmest November 10th), the high was 68 (with 1975, O'Hare's second warmest high of the date) with a low of 43. In 2004 the high was 62 with a low of 47 (O'Hare's other co-second warmest low of the date). The other warm highs were 68 degrees in 1975 (with 2010, O'Hare's second warmest high of the date), 64 degrees in 1998, 63 degrees in 1959 and 63 degrees in 1978. The other warm low was O'Hare's warmest low of the date of 48 degrees in 1992. The record high of 71 degrees and record warmest low of 52 degrees were set on the same warm day in 1949 at Midway. 24 of the past 34 highs (71%) were in the: 40s (11) and 50s (13). There were 13 consecutive highs in the 40s and 50s from 1983 through 1995. Seven highs (20%) were in the warm 60s. Three highs (9%) were in the cold 30s. Fact: O'Hare has never recorded a high of 70 degrees or higher on this date! 

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 with a low of 34, a five degree spread. In 1975 the high was a warm 68 with a low of 38, a 30 degree spread. In 1974 the high was 50 with a low of 46, a four degree spread. In 1973 the high was 41 with a cold low of 18, a cold day. In 1972 the high was 45 with a low of 41, a four degree spread. In 1969 the high was 46 with a low of 41, a five degree spread. In 1960 the high was a cold 37 with a low of 24, a cold day. In 1959 the high was a warm 63 degrees.

More recently, there were no large spreads. There were additional small spreads of three degrees in 1992 (51/48) and four degrees in 1985 (40/36).

On the cool side, in 1996 (O'Hare's coolest November 10th) the high was 31 (O'Hare's coolest high of the date) with a low of 24, a seven degree spread. In 1979 the high was 34 (O'Hare's second coolest high of the date) with a low of 22. In 1986 the high was 42 with the record low of 18 (with 1973, O'Hare's coldest low of the date). The other cold low was 20 degrees in 1991, O'Hare's second coldest low of the date. The other cool highs were 39 degrees in 1977 and 2008. The record coolest high of 28 degrees occurred in 1926 at the University of Chicago. 25 of the last 34 lows (74%) were in the: 20s (11) and 30s (14). One low (3%) was in the cold 10s. Eight lows (23%) were in the warm 40s. O'Hare's other cool November 10ths were: 1973 (high of 41, low of 18 (with 1986, O'Hare's coldest low of the date)) and 1960 (high of 37, low of 24). Fact: there has never been a low of 50 degrees or higher on this date in O'Hare's history!

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:08 and sunrise is at 6:38. Sunset is at 16:36 and twilight ends at 17:06. There's a total of 9 hours, 58 minutes of daylight today and 10 hours, 58 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:10 and sunrise is at 6:39. The moon is waning crescent. Illumination was 18% at midnight, will be 14% at noon and 10% at midnight tonight. Moonrise was at 2:39 this morning. Moonset is at 14:25 this afternoon. Moonrise is at 3:51 tomorrow morning. Moonlight time is 11 hours, 46 minutes which is 37 minutes shorter than yesterday.

Cool Fall began on November 2nd and runs for 29 days through November 30th. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 20s, 60s and 70s occur infrequently. Veteran's Day is tomorrow. Thanksgiving is in 12 days.