September 4: ORD

Today is September 4th. It's the 247th day of the year. 118 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 58. I've calculated the 31-year averages at 79 and 58.

On the hot side, in 1983 the high was the record high of 95 with a low of 67. Other hot highs were 92 in 1999, 91 in 1990, 89 three years ago and 88 in 1995. The record warmest low of 74 occurred in 1971. Another warm low was 71 in 1985. Over the last 31 years, 26 highs (84%) were: 70s (17) and 80s (9). Three highs were in the warmer 90s. Two 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 82 with a low of 52, a 30 degree spread. In 1974 the low was a cool 46. In 1973 the high was 76 with a low of 69, a seven degree spread. In 1971 the high was 89 with a warm low of 74, a hot day and year of the record warmest low. In 1969 the high was 76 with a warm low of 73, a mere three degree spread. In 1966 the high was 83 with a low of 53, a 30 degree spread. In 1962 the high was 85 with a low of 55, a 30 degree spread. In 1960 the high was 93 with a low of 72, a hot day.

More recently, there were large spreads of 32 degrees in 1982 (77/45) and 32 degrees in 1987 (85/53). There was a small spread of six degrees in 2008 (67/61). Two years ago it was cloudy and rainy. The rain was from the remnants of Hurricane Gustov. 2.91 inches fell at O'Hare.

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest highs were the two 60s: 66 in 1994 and 67 two years ago. The lowest temperatures were the three 40s: 45 in 1982 (co-record low), 45 in 1997 (co-record low) and 47 in 1984. The record coolest high of 60 occurred way back in 1902. Over the last 31 years, 27 lows (87%) were: 50s (15) and 60s (12). Three lows were in the cooler 40s and one low was in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:53 and sunrise is at 6:22. Sunset is at 19:22 and twilight ends at 19:51. There's a total of 13 hours of daylight today and 13 hours, 58 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:54 and sunrise is at 6:23. The moon is waning crescent. Illumination was 24% at midnight, will be 19% at noon and 15% at midnight tonight. Moonrise is at 1:33 this morning. Moonset is at 16:53 this afternoon and moonrise is at 2:47 tomorrow morning. Moonset is at 17:32 tomorrow afternoon. Moonlight time is 15 hours, 20 minutes which is 25 minutes shorter than yesterday.

Labor Day is in two days and Patriot Day is in seven days. Today marks the four year anniversary of the death of the Crocodile Hunter, Steve Irwin. He was killed by the poisonous barb of a sting ray while filming in the Australian choral reef. This behavior is considered a defensive act by the sting ray. -Bernie-