September 20: ORD

Today is September 20th. It's the 263rd day of the year. 102 days remain. It's week 38 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 72 and the normal low is 52. I've calculated the 31-year averages at 72 and 52.

On the hot side, in 1980 the high was 90 with a low of 67. In 1998 the high was 86 with a low of 65. Other hot highs were 85 in 1994 and 84 in 1985. The record high of 91 and record warmest low of 73 were set on the same day back in 1931, a time when the official readings were taken on the lakefront. The record high of 91 was first set way back in 1895. Over the last 31 years, there have been 24 highs (77%) in the: 60s (12) and 70s (12). Six highs have been in the warmer: 80s (5) and 90s (1). One high was in the cooler 50s.

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 89 with a low of 62, a hot day. In 1975 the high was a cool 60. In 1974 the high was 61 with a low of 55, a six degree spread. In 1970 the high was a hot 85 with a low of 63, a hot day. In 1967 the high was 85 with a low of 66, a hot day. In 1965 the high was 84 with a low of 69, a hot day. In 1962 the high was 60 with a low of 35, a cool day. That low of 35 was cooler than the record low. In 1960 the high was 65 with a low of 58, a seven degree spread. In 1959 the high was 88 with a low of 64, a hot day.

More recently, there were large spreads of 34 degrees in 1983 (78/44), 31 degrees in 1979 (79/48) and 30 degrees in 2003 (71/41). There were no small spreads of up to seven degrees.

On the cool side, in 1991 the high was 60 with the record low of 36. In 1982 the high was 55 with a low of 43. Another cool high was 60 in 1995. The record coolest high of 52 occurred back in 1901, a time when the official readings were taken on the lakefront. Over the last 31 years, 17 lows were in the 50s. Ten lows were in the cooler: 30s (1) and 40s (9). Four lows were in the warmer 60s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:11 and sunrise is at 6:39. Sunset is at 18:54 and twilight ends at 19:22. There's a total of 12 hours, 15 minutes of daylight today and 13 hours, 11 minutes between twilights. We are losing two to four minutes of daylight a day. Tomorrow twilight begins at 6:12 and sunrise is at 6:40. The moon is waxing gibbous. Illumination was 91% at midnight, will be 94% at noon and 96% at midnight tonight. Moonset is at 4:02 this morning. Moonrise is at 17:29 this afternoon. Moonset is at 5:01 tomorrow morning. Moonlight time is 10 hours, 33 minutes which is 37 minutes longer than yesterday.

Columbus Day is in 21 days. -Bernie-