November 4: ORD

Today is November 4th. It's the 308th day of the year. 57 days remain. It's week 44 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 54 and the normal low is 37. I've calculated the 33-year averages at 53 and 37.

On the warm side, in 1981 the high was 71 with a low of 54. Three years ago, in 2008, the high was 71 (our most recent 70s high) with a low of 50. Three decades earlier, in 1978, the high was 74 (same temperature and day of the record high set at Midway) with a low of 45. In 2005 the high was 70 with a low of 49. In 1994 the high was 65 with a low of 52. In 2003 the high was 70 with a low of 47. In 1987 the high was 68 with a low of 46. The record warmest low of 59 occurred in 1975 at Midway. 19 of the past 33 highs (58%) were in the: 40s (8) and 50s (11). Ten highs (30%) were in the warm: 60s (5) and 70s (5). Four highs (12%) were in the cold: 20s (1) and 30s (3). The last 60s high was ten years ago (61 in 2001). We've had three 70s highs since that most recent 60s high!

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1977 the low was a warm 50 degrees. In 1975 the high was 66 with a low of 55, a warm day and year of the record warmest low of 59 at Midway. In 1974 the high was 45 with a low of 40, a five degree spread. In 1972 the high was 44 with a low of 39, a five degree spread. In 1969 the high was a cold 42 with a low of 36, a six degree spread. In 1969 the high was a cold 42 with a low of 36, a six degree spread. In 1967 the high was a cold 37 with a low of 28, a cold day. In 1966 the low was a cold 24 degrees. In 1964 the high was a warm 71 with a low of 45, a warm day. In 1963 the high was 50 with a low of 45, a five degree spread. In 1962 the high was a cold 39 with a low of 33, a six degree spread. In 1958 the high was a warm 68 degrees.

More recently, there was a large spread of 39 degrees in 1999 (65/26). There were small spreads of four degrees in 1997 (41/37), five degrees in 1992 (38/33) and six degrees in 1985 (43/37).

On the cold side, in 1991 the high was 25 (O'Hare's only 20s high) with the record low of 11 (our only 10s low), a very winter-like day (26 degrees below normal) and by far the coldest November 4th in the history of O'Hare. Four years later, in 1995, the high was 33 with a low of 20. In 1982 the high was 31 with a low of 25, a six degree spread. Other cold highs were 38 in 1992, 41 in 1997 and 41 in 1998. The record coldest high of 24 occurred in 1951. 16 of the last 33 lows (49%) were in the 30s. Six lows (18%) were in the cold: 10s (1) and 20s (5). 11 lows (33%) were in the warm: 40s (8) and 50s (3). The following I wrote last year: Today (2010) I was witness to precipitation in the form of sleet. It melted shortly after hitting the ground. This occurred at about 15:45.

There's been two instances of back-to-back years in which temperatures were just about as opposite as they can be. First, in 1981 the high was 71 with a low of 54, overall 16.5 degrees ABOVE normal. Then in 1982 the high was 31 with a low of 25, overall 18 degrees BELOW normal. Second, in 1994 the high was 65 with a low of 52, overall 12.5 degrees ABOVE normal. Then in 1995 the high was 33 with a low of 20, overall 19.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 7:00 and sunrise is at 7:30. Sunset is at 17:43 and twilight ends at 18:13. There's a total of 10 hours, 13 minutes of daylight today and 11 hours, 13 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 7:02 and sunrise is at 7:31. The moon is waxing gibbous, having reached first quarter two days ago at 11:38. Illumination was 65% at midnight, will be 70% at noon and 74% at midnight tonight. Moonset was at 1:35 this morning. Moonrise is at 14:40 this afternoon. Moonset is at 2:35 tomorrow morning. Moonlight time is 10 hours, 55 minutes which is 36 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. Election Day is in four days. Veterans Day is in seven days. Thanksgiving is in 20 days.