November 13: ORD

Today is November 13th. It's the 317th day of the year. 48 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 50 and the normal low is 34. I've calculated the 33-year averages at 50 and 32.

On the warm side, in 1989 the high was the record high of 73 with a low of 45. Five years later, in 1994, the high was 65 with the record warmest low of 52. A year earlier, 1993, the high was 65 with a low of 45. In 1999 the high was 71 (our most recent 70s high) with a low of 37, a 34 degree spread. The other warm highs were 64 in 1978 and 63 in 2001. 24 of the past 33 highs (73%) were in the: 40s (8), 50s (8) and 60s (8). There were 11 consecutive highs in the 40s, 50s & 60s from 2000 through 2010. Two highs (6%) were in the warm 70s. Seven highs (21%) were in the cold: 20s (3) and 30s (4). The three 20s highs were the only ones in O'Hare's history on November 13. Our most recent 20s high was 27 in 1996 followed by our most recent 30s high, 37 in 1997. No highs have been below 40 from 1998 on.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1976 the high was 40 with a cold low of 17, a cold day. In 1975 the high was a cold 38 with a low of 32, a six degree spread. In 1974 the high was a cold 36 degrees. In 1973 the high was 61 with a warm low of 50, a warm day. In 1967 the high was a cold 38 degrees. In 1962 the high was 57 with a low of 26, a 31 degree spread. In 1960 the high was a warm 63 degrees. In 1959 the high was 35 with a low of 26, a cold day. In 1958 the high was 65 with a low of 48, a warm day.

More recently, there were no other large spreads. There was a small spread of three degrees in 1985 (46/43).

On the cold side, in 1986 the high was the record coldest high of 21 with the record low of 6. A decade later, in 1996, the high was 27 with a low of 17. In 1982 the high was 28 with a low of 20. In 1995 the high was 31 with a low of 18. Three years earlier, in 1992, the high was 36 with a low of 24. Five years later, in 1997, the high was 37 with a low of 24. In 1983 the high was also 37 with a low of 24. Note that the lows in the 10s (a.k.a. teens) happened in back-to-back years. 22 of the last 33 lows (67%) were in the: 20s (10) and 30s (12). Our most recent 20s lows were 29 in 2003 and 26 in 2004. There were six consecutive 20s & 30s lows from 2002 through 2007. Three lows (9%) were in the cold: 0s (1) and 10s (2). Just one pre-1978 10s low: 17 in 1976. Eight lows (24%) were in the warm: 40s (7) & 50s (1). Just one pre-1978 50s low: 50 in 1973.

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1992 the high was 36 with a low of 24, overall 12 degrees BELOW normal. Then in 1993 the high was 65 with a low of 45, overall 13 degrees ABOVE normal. In the second instance, in 1994 the high was 65 with a low of 52, overall 16.5 degrees ABOVE normal. Then in 1995 the high was 31 with a low of 18, overall 17.5 degrees BELOW normal. Also interesting is that all of this occurred in four consecutive years!

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:11 and sunrise is at 6:41. Sunset is at 16:34 and twilight ends at 17:04. There's a total of 9 hours, 53 minutes of daylight today and 10 hours, 53 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:12 and sunrise is at 6:42. The moon is waning gibbous, having passed full three days ago at 14:16 as the full Beaver (aka Frost) moon. Illumination was 95% at midnight, will be 92% at noon and 90% at midnight tonight. Moonset is at 9:16 this morning. Moonrise is at 18:41 tonight. Moonset is at 10:02 tomorrow morning. Moonlight time is 14 hours, 35 minutes which is the same as yesterday and is at it's peak.

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 11 days.