November 15: ORD

Today is November 15th. It's the 319th day of the year. 46 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. 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 49 and the normal low is 33. I've calculated the 33-year averages at 48 and 34.

On the warm side, in 1990 the high was 70 (O'Hare's only 70s high for the date) with a low of 52. In 2001 the high was 68 (our most recent 60s high) with a low of 54 (our most recent 50s low). In 1988 the high was 65 with a low of 47. The other warm highs were 63 in 1987 and 62 in 1981. The record high of 71 was set in 1971 at Midway. The record high of 71 was also set in 1955 and two years earlier in 1953, both at Midway. The record warmest low of 60 occurred in 1960 at Midway. 16 of the past 33 highs (49%) were in the 40s. 12 highs (36%) were in the warm: 50s (7), 60s (4) and 70s (1). Five highs (15%) were in the cold 30s, most recently 39 in 2000.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1976 the low was a cold 17 degrees. In 1972 the high was 38 with a low of 32, a mere six degree spread. In 1971 the high was a warm 68 with a low of 41, a warm day and year of the record high of 71 at Midway. In 1969 the high was 32 with a low of 20, a cold day. In 1968 the high was 46 with a low of 43, a mere three degree spread. In 1967 the high was 38 with a cold low of 20, a cold day. In 1964 the high was 62 with a low of 53, a warm day. In 1962 the low was a warm 45 degrees. In 1960 the high was 65 with a low of 55, a warm day and year of the record warmest low of 60 at Midway. In 1959 the high was 38 with a cold low of 13 degrees, a cold day. In 1958 the high was 61 with a low of 46, a warm day.

More recently, there were no large spreads of 30 degrees or more. There were small spreads of four degrees in 2002 (40/36), four degrees in 2003 (42/38), four degrees in 2006 (47/43), six degrees in 1993 (44/38), seven degrees in 1979 (47/40), seven degrees in 1985 (42/35), seven degrees in 1998 (46/39) and seven degrees three years ago, in 2008 (42/35).

On the cold side, in 1982 the high was 34 with a low of 13. In 1995 the high was 34 with a low of 20. Three years earlier, in 1992, the high was 36 with a low of 21. Five years later, in 1997, the high was 34 with a low of 24. The record low of 10 and record coldest high of 18 were set on the same cold day back in 1933. 19 of the last 33 lows (58%) were in the 30s. Eight lows (24%) were in the cold: 10s (1) and 20s (7). There was only one other 10s low in O'Hare's history (13 in 1959). Six lows (18%) were in the warm: 40s (4) and 50s (2). There were only two other 50s lows in the history of O'Hare: 55 in 1960 and 53 in 1964.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2000 the high was 39 with a low of 22, overall 10.5 degrees BELOW normal. Then in 2001 the high was 68 with a low of 54, overall 20 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:13 and sunrise is at 6:44. Sunset is at 16:32 and twilight ends at 17:02. There's a total of 9 hours, 48 minutes of daylight today and 10 hours, 49 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:15 and sunrise is at 6:45. The moon is waning gibbous. Illumination was 83% at midnight, will be 79% at noon and 74% at midnight tonight. Moonset is at 10:44 this morning. Moonrise is at 20:41 tonight. Moonset is at 11:20 tomorrow morning. Moonlight time is 14 hours, 3 minutes which is 20 minutes less 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. Thanksgiving is in nine days.