November 27: ORD

Today is November 27th. It's the 331st day of the year. 34 days remain. It's week 48 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 42 and the normal low is 27. I've calculated the 33-year averages at 45 and 30.

On the warm side, in 1990 the high was the record high of 67 with a low of 50. In 2006 the high was 62 (our most recent 60s high) with the record warmest low of 52. The former record warmest lows were 50 degrees in both 1879 and 1990. In 1989 the high was 63 with a low of 38. In 1998 the high was 64 with a low of 32, a 32 degree spread. Four years before, in 1994, the high was 59 with a low of 36. In 2005 the high was 55 (our most recent 50s high) with a low of 40, our only 40s low. In 1984 the high was 58 with a low of 35. 25 of the past 33 highs (76%) were in the: 30s (14) and 40s (11). Eight highs were in the warm: 50s (4) and 60s (4). Note the 60s highs in the back-to-back years of 1989 and 1990. The only other 60s high was 60 in 1960. O'Hare also had four highs in the cold 20s prior to 1978.

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 28 with a low of 18, a cold day. In 1976 the low was a cold 14 degrees. In 1973 the high was 54 with a low of 48, a spread of six degrees and warm day. In 1972 the high was 32 with a low of 25, a seven degree spread. In 1971 the high was 38 with a low of 32, a six degree spread. In 1970 the high was 42 with a warm low of 40, a two degree spread. In 1967 the high was a cold 29 degrees. In 1966 the high was a warm 57 degrees. In 1964 the high was a warm 54 with a a low of 22, a 32 degree spread. In 1960 the high was 60 with a low of 45, a warm day. In 1959 the high was a cold 29 with a low of 17, a cold day. In 1958 the high was 27 with a low of 12, a cold day.

More recently, there were no other large spreads. There were small spreads of two degrees in 1978 (35/33), three degrees in 1979 (38/35), five degrees in 1987 (43/38), seven degrees in 1980 (37/30) and seven degrees in 1983 (44/37).

On the cold side, in 2002 the high was 30 with a low of 14. In 1996 the high was 31 with a low of 15. The record low of 2 was last set back in 1930, having first being set way back in 1887. The record coldest high of 14 was set back in 1930. These records were set at a time when the official readings were taken adjacent to Lake Michigan. 27 of the last 33 lows (82%) were in the: 20s (13) and 30s (14). 12 consecutive lows from 1978 through 1989 were in the 20s & 30s. Our most recent 30s low was 37 in 2004. Three lows were in the cold 10s (a.k.a. teens). Three lows were in the warm: 40s (1) and 50s (2). Three lows prior to 1978 were in the 40s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:27 and sunrise is at 6:58. Sunset is at 16:24 and twilight ends at 16:55. There's a total of 9 hours, 26 minutes of daylight today and 10 hours, 28 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 6:28 and sunrise is at 6:59. The moon is waxing crescent, having passed new two days ago at 0:10. Illumination was 6% at midnight, will be 8% at noon and 12% at midnight tonight. Moonrise is at 9:23 this morning. Moonset is at 19:03 tonight. Moonrise is at 10:07 tomorrow morning. Moonlight time is 9 hours, 40 minutes which is 14 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. Pearl Harbor Day is in ten days.