September 16: ORD

Today is September 16th. It's the 259th day of the year. 106 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 74 and the normal low is 54. I've calculated the 31-year averages at 72 and 53.

On the hot side, in 1992 the high was 84 with a low of 70. Other hot highs were 86 in 1994, 85 in 1995 and 85 in 1997. Other warm lows were 66 in both 1987 and 1998. The record high of 92 was set in 1955. The record warmest low of 72 occurred back in 1907, a time when the official thermometer was located near the lakefront. Over the last 31 years, 16 highs were 70s. Five highs were in the warmer 80s. Ten highs were in the cooler: 50s (2) and 60s (8).

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1973 the high was a cool 59 with a low of 52, a seven degree spread. Also in 1973, there was a mere 0.04 inches of rain but a big 1.32 inches the following day, the 17th. There were also ten straight days of highs in the 70s (6th-15th). The month began with three 90s highs. In 1969 the high was 73 with a warm low of 66 degrees. In 1966 the high was 73 with a cool low of 40, a 33 degree spread. In 1965 the high was a cool 61. In 1963 the high was 85 with a low of 55, a 30 degree spread. In 1962 the high was a hot 86 with a low of 48, a 38 degree spread. In 1959 the high was a cool 56 with a low of 47, a cool day.

More recently, there were large spreads of 34 degrees in 1985 (76/42), 32 degrees in 2003 (82/50) and 30 degrees in 1979 (77/47). There was a small spread of seven degrees in 1987 (73/66).

On the cool side, in 1984 the high was 64 with the record low of 37. In 1981 the high was 59 with a low of 46. Other cool highs were 59 in 1993 and 61 in 1982. Another cool low was 42 in 1985. The record coolest high of 56 occurred in 1959. Over the last 31 years, 24 lows were: 40s (12) and 50s (12). One low was in the cooler 30s. 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 6:06 and sunrise is at 6:34. Sunset is at 19:01 and twilight ends at 19:29. There's a total of 12 hours, 27 minutes of daylight today and 13 hours, 23 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:07 and sunrise is at 6:35. The moon is waxing gibbous and reached first quarter yesterday morning at 50 minutes past midnight. Illumination was 60% at midnight, will be 65% at noon and 70% at midnight tonight. Moonrise is at 15:34 this afternoon. Moonset is at 58 minutes past midnight tonight and moonrise is at 16:09 tomorrow afternoon. Moonlight time is 8 hours, 26 minutes which is 41 minutes shorter than yesterday. Moonlight time has reached it's shortest of the next several days.

Citizenship day is tomorrow. -Bernie-