September 6: ORD

Today is September 6th. It's the 249th day of the year. 116 days remain. It's week 36 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 78 and the normal low is 57. I've calculated the 31-year averages at 80 and 59.

On the hot side, in 1990 the high was 96 with a low of 71. In 1985 the high was 93 with a low of 73. In 1998 the high was 92 with a low of 70. The record high of 97 was set in 1960. The record warmest low of 78 occurred way back in 1881, a time when the thermometer was located adjacent to Lake Michigan. Another warm low was 73 three years ago. Over the last 31 years, 24 highs (77%) were: 70s (10) and 80s (14). Three highs were in the warmer 90s. Four 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 1976 the high was 83 with a low of 47, a 36 degree spread. In 1971 the high was 87 with a low of 70, a hot day. In 1970 the high was 74 with a low of 67, a seven degree spread with 1.48 inches of rain. In 1969 the high was 78 with a low of 71, a seven degree spread. In 1967 the high was 78 with a cool low of 45, a 33 degree spread. In 1963 the high was 77 with a low of 43, a 34 degree spread. In 1962 the low was a cool 43. In 1960 the high was 95 with a low of 71, a hot day. 1960 was the year of the record high. In 1959 the high was 92 with a low of 69, a hot day.

More recently, there were large spreads of 31 degrees in 1984 (73/42), 31 degrees in 1991 (85/54) and 31 degrees in 2003 (81/50). There was a small spread of seven degrees in 1989 (75/68).

On the cool side, the coolest day was in 1988 as the high was 66 with a low of 43. Other cool highs were 67 in 1986, 68 in 1982 and 68 in 1993. Other cool lows were the record low of 42 in 1984, 47 in 2000 and 49 in 1986. The record coolest high of 61 occurred way back in 1885, a time when the thermometer was located adjacent to Lake Michigan. Over the last 31 years, 23 lows (74%) were: 50s (13) and 60s (10). Four lows were in the cooler 40s and four lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:55 and sunrise is at 6:24. Sunset is at 19:19 and twilight ends at 19:47. There's a total of 12 hours, 55 minutes of daylight today and 13 hours, 52 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:56 and sunrise is at 6:25. The moon is waning crescent. Illumination was 7% at midnight, will be 4% at noon and 2% at midnight tonight. Moonrise is at 4:06 this morning. Moonset is at 18:05 this afternoon and moonrise is at 5:25 tomorrow morning. Moonlight time is 13 hours, 59 minutes which is 46 minutes shorter than yesterday.

Labor Day is today and Patriot Day is in five days. -Bernie-