November 9: ORD

Today is November 9th. It's the 313th day of the year. 52 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 52 and the normal low is 35. I've calculated the 33-year averages at 52 and 36.

On the warm side, in 1999 the high was the record high of 74 with the record warmest low of 59. Three years later, in 2002, the high was 63 with a low of 53. Four years later (also five years ago), in 2006, the high was 68 with a low of 47. Three years later (also two years ago), in 2009, the high was 63 with a low of 50. In 1984 the high was 62 with a low of 49. The other warm highs were 69 last year, in 2010 and 66 in 2005. 29 of the past 33 highs (88%) were in the: 40s (14), 50s (6) and 60s (9). Our most recent 50s high was 53 in 2004. One high was in the warm 70s and three were in the cold 30s. There was only one more high in the 30s and 70s prior to 1978 (see the next section for specifics).

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 warm 66 degrees. In 1975 the high was 68 with a low of 52, a warm day. In 1973 the high was 34 with a low of 20, a cold day. In 1972 the high was 45 with a low of 41, a four degree spread. Also in 1972, the temperatures from the 9th to the 11th were the same (a high of 45 and low of 41 each day). On the 12th, the high was 46 with a low of 41. In 1971 the high was a cold 40 with a low of 34, a six degree spread. In 1970 the low was a warm 49 degrees. In 1969 the high was 48 with a low of 41, a seven degree spread. In 1968 the high was a cold 40 degrees. In 1966 the high was 63 with a warm low of 48, a warm day. In 1964 the high was a warm 71 with a low of 45, a warm day. In 1960 the low was a cold 23 degrees.

More recently, there were no other large spreads of at least 30 degrees. There were small spreads of four degrees in 1982 (46/42), five degrees in 1997 (45/40), six degrees in 1990 (40/34) and six degrees in 2000 (42/36).

On the cold side, in 1991 the high was 37 with the record low of 14. Five years earlier, in 1986, the high was 39 with a low of 21. In 2003 the high was 41 with a low of 20. In 1995 the high was 48 with a low of 17 (our most recent 10s low), a 31 degree spread. The other cold highs were 39 three years ago (in 2008), 40 in 1990 and 40 in 1996. The record coldest high of 31 was set in 1957 at Midway. 28 of the last 33 lows (85%) were in the: 20s (8), 30s (8) and 40s (12). Our most recent 20s low was 20 in 2003. Two lows were in the cold 10s (aka teens), the only ones so far at O'Hare. Three lows were in the warm 50s. There's just one other 50s low, pre-1978 (see 1975 above).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2002 the high was 63 with a low of 53, overall 14 degrees ABOVE normal. Then in 2003 the high was 41 with a low of 20, overall 13.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:06 and sunrise is at 6:36. Sunset is at 16:38 and twilight ends at 17:07. There's a total of 10 hours, 2 minutes of daylight today and 11 hours, 1 minute between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:08 and sunrise is at 6:37. The moon is waxing gibbous and will be full tomorrow at 14:16 as the full Beaver (aka Frost) moon. Illumination was 98% at midnight, will be 99% at noon and 100% at midnight tonight. Moonset is at 5:31 this morning. Moonrise is at 15:49 this afternoon. Moonset is at 6:30 tomorrow morning. Moonlight time is 13 hours, 42 minutes which is 29 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 in two days. Thanksgiving is in 15 days.