November 4: ORD

Today is November 4th. It's the 309th day of the year. 57 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. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. 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 34-year averages at 53 and 37.

On the warm side, in 1981 (O'Hare's warmest November 4th) the high was 71 with a low of 54 (O'Hare's second warmest low of the date). In 2008 (with 1975, O'Hare's second warmest November 4th) the high was 71 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. The other warm highs were 68 degrees in 1958 and again in 1987. The other warm low of 50 degrees occurred in 1977. The record warmest low of 59 degrees occurred in 1975 at Midway. 20 of the past 34 highs (59%) were in the: 40s (8) and 50s (12). Ten highs (29%) 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 11 years ago (61 degrees in 2001). We've had three 70s highs since that most recent 60s high! O'Hare's second warmest November 4th (with 2008) was in 1975 as the high was 66 with a low of 55 (O'Hare's warmest low of the date). The other warm day was in 1964 as the high was 71 with a low of 45.

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 cool side, in 1991 (O'Hare's coolest November 4th) the high was 25 (O'Hare's coolest and only 20s high) with the record low of 11 (our only 10s low), a very winter-like day (28 degrees below normal). Four years later, in 1995 (O'Hare's second coolest November 4th), the high was 33 with a low of 20 (O'Hare's second coldest low of the date). In 1982 (O'Hare's third coolest November 4th) the high was 31 (O'Hare's second coolest high of the date) with a low of 25, a six degree spread. The other cold low was 24 degrees in 1966. The other cool highs were 38 degrees in 1992, 39 degrees in 1962, 41 degrees in 1997, 41 degrees in 1998 and 42 degrees in 1969. The record coldest high of 24 degrees occurred in 1951 at Midway. 17 of the last 34 lows (50%) were in the 30s. Six lows (18%) were in the cold: 10s (1) and 20s (5). 11 lows (32%) were in the warm: 40s (8) and 50s (3). The other cool day was in 1967 as the high was 37 with a low of 28. 

The following I wrote two years ago in 2010: "Today I was witness to precipitation in the form of sleet. It melted shortly after hitting the ground. This occurred at about 15:45." The National Weather Service posted a write-up this year (on 10/18/12) about what graupel is. It's quite possible that what I saw was graupel and not sleet because as I noted, the precipitation melted after it hit the ground. Usually sleet will not melt right away after hitting the ground.  

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 6:01 and sunrise is at 6:31. Sunset is at 16:43 and twilight ends at 17:12. There's a total of 10 hours, 12 minutes of daylight today and 11 hours, 11 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:03 and sunrise is at 6:32. The moon is waning gibbous. Illumination was 76% at midnight, will be 72% at noon and 67% at midnight tonight. Moonset is at 11:15 this morning. Moonrise is at 21:20 tonight. Moonset is at 11:51 tomorrow morning. Moonlight time is 13 hours, 55 minutes which is 18 minutes shorter than yesterday.

Cool Fall began on November 2nd and runs for 29 days through November 30th. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 10s and 20s occur infrequently. Standard Time returns today. Election Day is in two days. Veteran's Day is in seven days.