October 30: ORD

Today is October 30th. It's the 303rd day of the year. 62 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 57 and the normal low is 39. I've calculated the 32-year averages at 61 and 40.

On the warm side, in 1999 the high was 76 with a low of 56. A decade earlier, in 1989, the high was 75 with a low of 55. In 2004 the high was 72 with a low of 50. In 1990 the high was 73 with a low of 48. In 1998 the high was 65 with a low of 56. In 1981 the high was 75 with a low of 45, a 30 degree spread. The other warm highs were 72 in 1987, 70 in 2003 and 70 in 2006. The record high of 85 was set in 1950 at Midway. The record warmest low of 62 occurred in 1974 at Midway. 27 of the past 32 highs (84%) were in the: 50s (7), 60s (12) and 70s (8). Three years in a row (1983-1985) featured highs in the 50s. For 3 of 4 years, from 1987-1990 and from 2003-2006, highs were in the 70s. The more recent occurrence featured eight consecutive years (2003-2010) of highs in the 60s & 70s. Five highs were in the cold 40s. Four of the eight highs from 1988 through 1995 were in the 40s. Our most recent 50s high (52 in 2001) was followed by our most recent 40s high (48 in 2002).

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1978 the high was a warm 69 degrees. In 1976 the high was 49 with a low of 42, a seven degree spread. In 1974 the high was 76 with a low of 62, a warm day. 1974 was also the year of the record warmest low, also of 62 at Midway. In 1971 the high was 80 with a low of 55, a warm day. In 1968 the low was a cold 27 degrees. In 1966 the high was 52 with a cold low of 22, a 30 degree spread. In 1965 the high was a warm 69 degrees. In 1964 the high was 58 with a cold low of 24, a 34 degree spread. In 1963 the high was 58 with a cold low of 27, a 31 degree spread. In 1960 the low was a warm 51 degrees.

More recently, there were large spreads of 36 degrees in 1987 (72/36), 32 degrees in 2006 (70/38), 31 degrees three years ago, in 2008 (62/31) and 30 degrees in 2003 (70/40). There were small spreads of four degrees in 1992 (46/42), five degrees in 1995 (45/40), five degrees in 2001 (52/47) and seven degrees in 2002 (48/41).

On the cold side, in 1988 the high was 45 with the record low of 21, our most recent 20s low. Five years later, in 1993, the high was 40 with a low of 30. The other cold low was 24 in 1980. The other cold high was 45 in 1995. The record coldest high of 28 occurred back in 1917, a time when the official readings were taken adjacent to Lake Michigan. 25 of the last 32 lows (78%) were in the: 30s (13) and 40s (12). Lows were in the 30s & 40s for: eight consecutive years from 1990 through 1997 and six consecutive years from 2005 through 2010. Two lows were in the cold 20s. Five lows were in the warm 50s, most recently 50 in 2004.

There's an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1988 the high was 45 with a low of 21, overall 15 degrees BELOW normal. Then in 1989 the high was 75 with a low of 55, overall 17 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:55 and sunrise is at 7:24. Sunset is at 17:50 and twilight ends at 18:19. There's a total of 10 hours, 26 minutes of daylight today and 11 hours, 24 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:56 and sunrise is at 7:25. The moon is waxing crescent. Illumination was 16% at midnight, will be 21% at noon and 25% at midnight tonight. Moonrise is at 11:46 this morning. Moonset is at 21:16 tonight. Moonrise is at 12:34 tomorrow afternoon. Moonlight time is 9 hours, 30 minutes which is seven minutes longer than yesterday.

Warm Fall began September 22 and runs for 41 days through November 1. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 30s and 40s occur infrequently. Halloween is tomorrow. Election Day is in nine days. Veterans Day is in 12 days.