September 18: ORD

Today is September 18th. It's the 261st day of the year. 104 days remain. It's week 38 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 73 and the normal low is 54. I've calculated the 31-year averages at 76 and 53.

On the hot side, in 1985 the high was 87 with a low of 67. Three years later, in 1988, the high was 86 with a low of 67. Three years ago the high was 88 with a low of 63. Another hot high was 86 in 2000. The record high of 94 was set in 1955. The record warmest low of 71 occurred in 1965. Over the last 31 years, the tally of highs has been just about equal. Nine highs were 60s, 11 highs were 70s and 11 highs were 80s. The last 60s high of 69 occurred nine years ago in 2001.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1978 the low was a warm 66 degrees. In 1977 the low was a warm 69 degrees. In 1976 the high was 78 with a low of 48, a 30 degree spread. In 1965 the high was 85 with a low of 68, a hot day and year of the record warmest low. In 1963 the high was a hot 89 degrees. In 1962 the high was 75 with a low of 45, a 30 degree spread. In 1959 the low was a cool 40, which is equal to the record low.

More recently, there were large spreads of 35 degrees in 2000 (86/51), 31 degrees in 1984 (74/43), 30 degrees in 1980 (75/45) and 30 degrees in 1997 (83/53). There was a small spread of four degrees in 1986 (65/61).

On the cool side, in 1981 the high was 60 with a low of 42. Another cool low was 42 degrees a decade later in 1991. The record low of 40 was set in 1903. The record coolest high of 54 was set way back in 1901. The last 40s low of 48 occurred 11 years ago in 1999.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:08 and sunrise is at 6:36. Sunset is at 18:58 and twilight ends at 19:26. There's a total of 12 hours, 22 minutes of daylight today and 13 hours, 18 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:09 and sunrise is at 6:37. The moon is waxing gibbous. Illumination was 78% at midnight, will be 82% at noon and 85% at midnight tonight. Moonset was at 2:00 this morning. Moonrise is at 16:39 this afternoon. Moonset is at 3:01 tomorrow morning. Moonlight time is 9 hours, 21 minutes which is 32 minutes longer than yesterday.

Columbus Day is in 23 days. -Bernie-