September 14: ORD

Today is September 14th. It's the 257th day of the year. 108 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 54. I've calculated the 31-year averages at 74 and 55.

On the hot side, in 1994 the high was 90 with a low of 73. Three years earlier, in 1991, the high was 90 with a low of 67. Another warm low was 68 in 1998. The record high of 99 and record warmest low of 76 were set on the same hot day back in 1939. Over the last 31 years, 15 highs were in the 70s. Seven highs were in the warmer: 80s (5) and 90s (2). Nine 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 1975 the low was a cool 41. In 1974 the low was a cool 40, equal to the record low. In 1971 the high was a hot 90 with a low of 58, a 32 degree spread. In 1970 the high was a cool 59 with a low of 55, a four degree spread. In 1969 the low was a warm 68. In 1964 the high was 80 with a cool low of 42, a 38 degree spread. In 1963 the high was 70 with a cool low of 38. That low of 38 was cooler than the record low. In 1961 the high was a cool 63.

More recently, there were large spreads of 31 degrees in 1988 (81/50), 30 degrees in 1987 (76/46) and 30 degrees in 2002 (83/53). There was a small spread of seven degrees in 1998 (75/68). Last year we received more rain from the remnants of Hurricane Ike. O'Hare recorded 1.44 inches. Cincinnati had a peak wind gust of 74 miles an hour, causing power outages.

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest temperature was the record low of 40, set in 1985. The coolest high temperatures were 60 in 1996 and 63 in 2001. The record coolest high of 54 occurred way back in 1923, a time when the official readings were taken on the lakefront. Over the last 31 years, 17 lows were 50s. Eight lows were in the cooler 40s. Six lows were in the warmer: 60s (5) and 70s (1).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:04 and sunrise is at 6:32. Sunset is at 19:05 and twilight ends at 19:33. There's a total of 12 hours, 33 minutes of daylight today and 13 hours, 29 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:05 and sunrise is at 6:33. The moon is waxing crescent and reaches first quarter tomorrow night at 50 minutes past midnight. Illumination was 40% at midnight, will be 45% at noon and 50% at midnight tonight. Moonrise is at 13:59 this afternoon. Moonset is at 23:00 tonight and moonrise is at 14:50 tomorrow afternoon. Moonlight time is 9 hours, 1 minute which is 8 minutes shorter than yesterday.

Citizenship day is in three days. -Bernie-