September 7: ORD

Today is September 7th. It's the 250th day of the year. 115 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 77 and the normal low is 57. I've calculated the 31-year averages at 79 and 59.

On the hot side, in 1985 the high was 99 with a low of 73. Other warm highs were 90 in 1984, 90 in 1991 and 89 in 2002. The record high of 100 was set in 1960. The record warmest low of 78 occurred way back in 1922, a time when the thermometer was located adjacent to Lake Michigan. Another warm low was 70 three years ago. Over the last 31 years, 24 highs (77%) were: 70s (13) and 80s (11). 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 1978 the high was a hot 92. In 1972 the high was 74 with a low of 68, a six degree spread. In 1971 the high was a hot 92 with a low of 68, a hot day. In 1970 the high was 88 with a warm low of 73, a hot day. In 1968 the high was 79 with a low of 47, a 32 degree spread. In 1967 the high was 80 with a low of 44, a 36 degree spread. In 1966 the high was 76 with a low of 45, a 31 degree spread. In 1964 the high was a hot 94 with a low of 65, a hot day. There's also another interesting thing about 1964: on the 5th the low was 46, so there was an incredible 48 degree swing to a high of 94 today. In 1962 the high was 78 with a cool low of 39, a 39 degree spread. That low of 39 was colder than the record low. In 1960 the high was 99 with a low of 73, a hot day. 1960 was the year of the record high, occurring at Midway. In 1959 the high was 96 with a low of 74, a hot day.

More recently, there were large spreads of 33 degrees in 1988 (77/44), 30 degrees in 1999 (80/50) and 30 degrees in 2002 (89/59). There were no small spreads of up to seven degrees.

On the cool side, the coolest day was in 1986 as the high was 66 with the record low of 42. Another cool high was 66 in 1979. Other cool lows were 44 in 1988 and 49 in 1993. The record coolest high of 61 occurred way back in 1924, a time when the thermometer was located adjacent to Lake Michigan. Over the last 31 years, 26 lows (84%) were: 50s (14) and 60s (12). Three 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 5:56 and sunrise is at 6:25. Sunset is at 19:17 and twilight ends at 19:45. There's a total of 12 hours, 52 minutes of daylight today and 13 hours, 49 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:58 and sunrise is at 6:26. The moon is waning crescent and will be new tomorrow morning at 5:30. Illumination was 2% at midnight, will be 1% at noon and 0% at midnight tonight. Moonrise is at 5:25 this morning. Moonset is at 18:35 this afternoon and moonrise is at 6:44 tomorrow morning. Moonlight time is 13 hours, 10 minutes which is 49 minutes shorter than yesterday.

Patriot Day is in four days and Grandparent's Day is in five days. -Bernie-