November 17: ORD

Today is November 17th. It's the 322nd day of the year. 44 days remain. It's week 46 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. 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 47 and the normal low is 32. I've calculated the 34-year averages at 47 and 31.

On the warm side, in 2004 the high was 63 with a low of 54 (with 1958, O'Hare's second warmest low of the date). In 1979 the high was 69 with a low of 41. In 2001 the high was 66 with a low of 38. The other warm high of 64 degrees occurred in 1987. The other warm lows were 46 degrees in 1969 and 44 degrees three years ago in 2009. The record high of 74 degrees was originally set in 1952 and tied in 1971 and then again in 1975, all at Midway. The record warmest low of 60 degrees occurred in 1952 at Midway. 22 of the past 34 highs (65%) were in the: 40s (13) and 50s (9). There were seven consecutive 40s and 50s highs from 1980 through 1986. Our most recent 50s high was 54 degrees in 2003. Four highs (12%) were in the warm 60s. Eight highs (23%) were in the cold: 20s (1) and 30s (7). O'Hare's warmest November 17th was in 1958 as the high was 71 (with 1971, O'Hare's warmest high of the date) and low of 54 (with 2004, O'Hare's second warmest low of the date). The second warmest 11/17 was in 1963 as the high was 69 with a low of 55 (O'Hare's warmest low of the date). The third warmest 11/17 was in 1971 as the high was 71 (with 1958, O'Hare's warmest high of the date) and low of 54. 1958 and 2004 had lows of 54 degrees, O'Hare's second warmest lows of the date. The other warm days were in: 1975 (high of 69, low of 49) and 1966 (high of 66, low of 45). The second warmest highs of 69 degrees occurred in 1963, 1975 and 1979.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1975 the high was 69 with a low of 49, a warm day and year of the record high of 74 at Midway. In 1972 the high was 36 with a low of 31, a five degree spread. In 1971 the high was 71 with a low of 50, a warm day. In 1969 the high was 51 with a warm low of 46, a five degree spread. In 1968 the high was 42 with a low of 39, a mere three degree spread. In 1966 the high was 66 with a low of 45, a warm day. In 1963 the high was 69 with a low of 55, a warm day. In 1961 the high was 36 with a low of 31, a five degree spread. In 1959 the high was 13 with a low of 2, a cold day and year of both the record low of 3 degrees and record coldest high of 14 at Midway. In 1958 the high was 71 with a low of 54, a warm day.

More recently, there were no large spreads. There were small spreads of three degrees three years ago in 2009 (47/44), five degrees in 2000 (32/27), six degrees in 1995 (38/32) and six degrees in 2006 (40/34).

On the cool side, in 2005 (O'Hare's second coolest November 17th) the high was 28 (O'Hare's second coolest high and only 20s high in its history for the date) with a low of 15. In 1989 the high was 34 with a low of 15. Those lows of 15 degrees are O'Hare's second coldest of the date. In 1997 the high was 34 with a low of 17 (O'Hare's third coldest low of the date). The other cold high was 32 degrees occurred in 2000. The record low of 3 degrees and record coolest high of 14 degrees were set on the same cold day in 1959 at Midway. 28 of the last 34 lows (82%) were in the: 20s (11) and 30s (17). Three lows were in the cold 10s (a.k.a. teens). These 10s lows occurred between 1989 and 2005. Three lows were in the warm: 40s (2) and 50s (1). O'Hare's coolest November 17th was in 1959 as the high was 13 (O'Hare's only 10s (a.k.a. teens) high of the date)) and low of 2 (O'Hare's only single digit low of the date). 

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2004 the high was 63 with a low of 54, overall 18.5 degrees ABOVE normal. Then in 2005 the high was 28 with a low of 15, overall 18.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:17 and sunrise is at 6:47. Sunset is at 16:30 and twilight ends at 17:00. There's a total of 9 hours, 43 minutes of daylight today and 10 hours, 43 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 6:18 and sunrise is at 6:48. The moon is waxing crescent. Illumination was 16% at midnight, will be 20% at noon and 25% at midnight tonight. Moonrise was at 10:31 this morning. Moonset is at 20:40 tonight. Moonrise is at 11:13 tomorrow morning. Moonlight time is 10 hours, 9 minutes which is 20 minutes longer 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. Thanksgiving is in five days. Pearl Harbor Day is in 20 days.