September 30: ORD

Today is September 30th. It's the 273rd day of the year. 92 days remain. It's week 39 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.

According to the National Climatic Data Center (NCDC), the normal high is 69 and the normal low is 48. I've calculated the 31-year averages at 72 and 48.

On the warm side, in 2002 the high was 85 with the near-record warmest low of 68. The record warmest low is 69 degrees, set in 1971. In 1995 the high was 84 with a low of 65. In 1982 the high was 85 with a low of 58. Three years ago the high was 83 with a low of 59. Other warm highs were 83 in both 1981 and 1994. It was 82 in 1991 and 81 in 1983. The record high of 92 was set in 1971. Over the last 31 years, 29 highs (94%) were: 60s (10), 70s (11) and 80s (8). Two years ago we had just the second 50s high of the last 31 years and the second one of the last seven years.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1976 the high was 77 with a low of 47, a 30 degree spread. In 1973 the high was 65 with a warm low of 60, a five degree spread. In 1972 the high was 53 with a low of 36, a cool day. In 1971 the high was 92 with a low of 65, a hot day. 1971 was the year of the record high and record warmest low. In 1968 the high was 80 with a low of 50, a 30 degree spread. In 1964 the low was a cool 36 degrees. In 1963 the high was 77 with a low of 45, a 32 degree spread. In 1962 the high was 70 with a cool low of 36, a 34 degree spread. In 1961 the high was 75 with a cool low of 44, a 31 degree spread. In 1960 the high was a cool 57 degrees.

More recently, there were large spreads of 36 degrees in 2004 (72/36), 34 degrees in 1989 (77/43), 33 degrees in 1983 (81/48), 31 degrees in 1994 (83/52), 31 degrees in 1996 (78/47) and 30 degrees in 1991 (82/52). There were no small spreads of up to seven degrees.

On the cool side, in 1984 the high was 60 with the record low of 29, a 31 degree spread. In 1993 the high was 61 with a low of 31, a 30 degree spread. In 2003 the high was 56 with a low of 39. Another cool low was 36 in 2004. The record coolest high of 44 was set way back in 1899, a time when the official readings were taken adjacent to Lake Michigan. 24 of the last 31 lows were: 40s (13) and 50s (11). Five lows were in the cooler: 20s (1) and 30s (4). Two lows were in the warmer 60s. The last 30s low was 36 in 2004. The year earlier, 2003, had a low of 39. Still a year before that, in 2002, the low was only 68. The only other 60s low was 65 in 1995. Two and three years prior to 1995 (1993 and 1992), the other two 30s lows occurred (31 and 39 degrees).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:21 and sunrise is at 6:49. Sunset is at 18:37 and twilight ends at 19:04. There's a total of 11 hours, 48 minutes of daylight today and 12 hours, 43 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:22 and sunrise is at 6:50. The moon reaches last quarter tonight at 22:52. Illumination was 60% at midnight, will be 55% at noon and 49% at midnight tonight. Moonset is at 14:02 this afternoon. Moonrise is at 23:19 tonight. Moonset is at 14:47 tomorrow afternoon. Moonlight time is 14 hours, 43 minutes which is 11 minutes shorter than yesterday.

Columbus Day is in 11 days. -Bernie-