September 13: ORD

Today is September 13th. It's the 256th day of the year. 109 days remain. It's week 37 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 75 and the normal low is 55. I've calculated the 31-year averages at 77 and 58.

On the hot side, in 2005 the high was 94 with a low of 71. In 1994 the high was 88 with a low of 66. Another warm high was 90 in 1998. Other warm lows were 70 in 1982, 68 (1993, 2003 and two years ago) and 67 in 1980. The record high of 98 was set back in 1939. The record warmest low of 75 occurred back in 1927, a time when the official readings were taken on the lakefront. Over the last 31 years, 22 highs (71%) were: 70s (11) and 80s (11). Two highs were in the warmer 90s and seven highs were in the cooler 60s.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1978 the high was 86 with a warm low of 67, a hot day. In 1975 the high was 63 with a low of 40, a cool day. In 1974 the high was a cool 59 with a low of 44, a cool day. In 1972 the low was a warm 67. In 1970 the high was a cool 59 with a low of 52, a seven degree spread. In 1964 the high was 70 with a cool low of 37, a 33 degree spread and cool day. That low of 37 was cooler than the record low. In 1963 the high was 62 with a low of 43, a cool day. In 1962 the high was 91 with a low of 71, a hot day.

More recently, there were large spreads of 33 degrees in 1998 (90/57) and 32 degrees in 2000 (79/47). There were small spreads of five degrees in 2006 (65/60), seven degrees in 1989 (60/53) and seven degrees two years ago (75/68). Two years ago we were getting lots of rain from the remnants of Hurricane Ike. O'Hare recorded 6.64 inches of rain.

On the cool side, in 1985 the high was 64 with a low of 42. Other cool lows were the four others in the 40s, the coolest of these was 47 degrees, occurring in 2000. Three lows were 48 degrees. The record low of 39 was set way back in 1890. Other cool highs were the coolest reading of 60 in 1989 and another high of 64 in 1996. The record coolest high of 55 occurred way back in 1880, a time when the official readings were taken on the lakefront. Over the last 31 years, 24 lows (77%) were: 50s (12) and 60s (12). Five lows were in the cooler 40s and two lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:03 and sunrise is at 6:31. Sunset is at 19:06 and twilight ends at 19:35. There's a total of 12 hours, 35 minutes of daylight today and 13 hours, 32 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:04 and sunrise is at 6:32. The moon is waxing crescent. Illumination was 30% at midnight, will be 35% at noon and 40% at midnight tonight. Moonrise is at 12:58 this afternoon. Moonset is at 22:07 tonight and moonrise is at 13:59 tomorrow afternoon. Moonlight time is 9 hours, 9 minutes which is 21 minutes shorter than yesterday.

Citizenship day is in four days. -Bernie-