September 5: ORD

Today is September 5th. It's the 248th day of the year. 117 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 58.

On the hot side, in 1983 the high was 95 with a low of 68. In 1985 the high was 92 with a low of 71. Other hot highs were 92 in 1999, 90 in 1995 and 90 in 2007. The record high of 98 was set way back in 1899. The record warmest low of 77 occurred back in 1912. Another warm low was 71 in 1990. Over the last 31 years, 22 highs (71%) were: 70s (9) and 80s (13). Five 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 1978 the high was 88 with a low of 57, a 31 degree spread. In 1974 the high was 72 with a cool low of 42, a 30 degree spread. In 1971 the high was 88 with a low of 70, a hot day. In 1969 the low was a warm 72. In 1967 the high was 78 with a low of 48, a 30 degree spread. In 1964 the high was 79 with a low of 46, a 33 degree spread. In 1962 the high was 67 with a cool low of 42, a cool day. In 1960 the low was a warm 70. In 1959 the high was 92. in 1959, today was the start of five straight days of highs in the 90s.

More recently, there were large spreads of 35 degrees in 1998 (87/52), 30 degrees in 1987 (88/58) and 30 degrees in 1999 (92/62). There was a small spread of seven degrees in 1994 (65/58).

On the cool side, the coolest day was in 1988 as the high was 64 with the co-record low of 44. Other cool highs were 65 in 1994, 67 in 2000 and 69 in 1984. Other cool lows were the other co-record low of 44 in 1984, 48 in 1997 and 48 in 2003. The record coolest high of 62 occurred way back in 1909. Over the last 31 years, 25 lows (81%) were: 50s (17) and 60s (8). Four 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 5:54 and sunrise is at 6:23. Sunset is at 19:20 and twilight ends at 19:49. There's a total of 12 hours, 57 minutes of daylight today and 13 hours, 55 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:55 and sunrise is at 6:24. The moon is waning crescent. Illumination was 15% at midnight, will be 11% at noon and 7% at midnight tonight. Moonrise is at 2:47 this morning. Moonset is at 17:32 this afternoon and moonrise is at 4:06 tomorrow morning. Moonset is at 18:05 tomorrow night. Moonlight time is 14 hours, 45 minutes which is 35 minutes shorter than yesterday.

Labor Day is tomorrow and Patriot Day is in six days. -Bernie-