November 1: ORD

Today is November 1st. It's the 305th day of the year. 60 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 56 and the normal low is 38. I've calculated the 33-year averages at 56 and 39.

On the warm side, in 2000 the high was 73 (our most recent 70s high) with a low of 53. A year later, in 2001, the high was 66 (our most recent 60s high) with a low of 58. In 1990 the high was 73 with a low of 48. In 1982 the high was 67 with a low of 51. In 1999 the high was 73 with a low of 45. Note that all three 70s highs were 73 degrees. The back to back to back warm years were 1999 (12 degrees above normal), 2000 (16 degrees above normal) and 2001 (15 degrees above normal). From the warmth of 1982 to 1990 was an eight year wait. From the warmth of 1990 to 1999 was a nine year wait. It's been ten years (a decade) since the warmth of 2001. That's how rare a double-digit above normal day is on November 1st! The other warm lows were 51 in 1985 and 51 in 1998. The record high of 81 was set in 1950 at Midway. The record warmest low of 60 occurred in 1933, a time when the official readings were taken adjacent to Lake Michigan. 14 of the past 33 highs (43%) were in the 50s. 11 highs (33%) were in the warm: 60s (8) and 70s (3). Eight highs (24%) were in the cold: 30s (1) and 40s (7). The past nine consecutive years (2002-2010) have produced highs in the 40s (a third of them) and 50s (two-thirds of them).

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 61 with a warm low of 58, only a three degree spread and warm day. In 1976 the low was a cold 26 degrees. In 1975 the high was 59 with a warm low of 52, a seven degree spread. In 1974 the high was 74 with a low of 54, a warm day. In 1972 the high was 51 with a low of 45, a six degree spread. In 1971 the high was a warm 70 with a low of 35, a 35 degree spread. In 1969 the high was 50 with a low of 44, a six degree spread. In 1968 the high was a warm 71 with a low of 47, a warm day. In 1966 the high was a cold 41 degrees. In 1962 the low was a cold 24 degrees. In 1960 the high was 45 with a low of 40, a five degree spread.

More recently, there was a large spread of 41 degrees in 1984 (67/26). There were small spreads of three degrees in 2004 (51/48), four degrees in 2003 (49/45), five degrees in 1998 (56/51), six degrees in 1992 (48/42), six degrees three years ago, in 2008 (54/48) and seven degrees in 1985 (58/51).

On the cold side, in 1996 the high was 38 (O'Hare's only 30s high) with a low of 25. In 2002 the high was 40 with a low of 25. Four years later (and five years ago) in 2006, the high was 42 with a low of 27 (our most recent 20s low). In 1993 the high was 46 with a low of 23. The other cold low was 26 in 1984. The record low of 21 was set way back in 1879, a time when the official readings were taken adjacent to Lake Michigan. The record coldest high of 35 occurred in 1954 at Midway. 22 of the last 33 lows (67%) were in the: 30s (11) and 40s (11). For seven consecutive years, from 1986 through 1992, lows were in the 30s & 40s. Six lows (18%) were in the cold 20s. Five lows (15%) were in the warm 50s. Our most recent 50s low was 58 in 2001. Three of the four years from 1998 to 2001 had lows in the 50s.

There's an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2001 the high was 66 with a low of 58, overall 15 degrees ABOVE normal. Then in 2002 the high was 40 with a low of 25, overall 14.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:57 and sunrise is at 7:26. Sunset is at 17:47 and twilight ends at 18:16. There's a total of 10 hours, 21 minutes of daylight today and 11 hours, 19 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:58 and sunrise is at 7:27. The moon is waxing crescent and will reach first quarter tomorrow at 11:38. Illumination was 35% at midnight, will be 40% at noon and 46% at midnight tonight. Moonrise is at 13:13 this afternoon. Moonset is at 23:29 tonight. Moonrise is at 13:46 tomorrow afternoon. Moonlight time is 10 hours, 16 minutes which is 27 minutes longer than yesterday.

Warm Fall began September 22 and runs for 41 days through November 1 (today). High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 30s and 40s occur infrequently. Election Day is in seven days. Veterans Day is in ten days.