September 29: ORD

Today is September 29th. It's the 272nd day of the year. 93 days remain. It's week 39 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 69 and the normal low is 49. I've calculated the 31-year averages at 70 and 49.

On the warm side, in 1982 the high was 83 with a low of 63. In 2002 the high was 84 with a low of 60. In 1979 the high was 85 with a low of 58. In 1986 the high was 77 with a low of 64. Another warm high was 81 in 1983. To round out the 80s, it was 80 in 1995 and 2007. The record high of 99 was set in 1953 and the record warmest low of 69 occurred in 1904, a time when the official readings were taken adjacent to Lake Michigan. Over the last 31 years, 21 highs were: 60s (12) and 70s (9). Six highs were in the warmer 80s and four highs were 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 1971 the high was 80 with a warm low of 65, a warm day. In 1970 the high was 72 with a low of 39, a 33 degree spread. In 1967 the high was a cool 47 with a low of 41, a six degree spread. In 1964 the high was 67 with a cold low of 32, a 35 degree spread. In 1962 the high was 66 with a cool low of 36, a 30 degree spread. In 1961 the high was 66 with a cold low of 32, a 34 degree spread. The lows of 32 in 1964 and 1961 are equal to the record.

More recently, there were large spreads of 31 degrees in 1983 (81/50) and 30 degrees three years ago (80/50). There were no small spreads of up to seven degrees.

On the cool side, in 1984 the high was 55 with the record low of 32. In 1993 the high was 54 with a low of 37. Other cool lows were 36 in 1992 and 37 in 2006. The record coolest high of 44 was set way back in 1899, a time when the official readings were taken adjacent to Lake Michigan. 23 of the last 31 lows were: 40s (10) and 50s (13). Five lows were in the cooler 30s and three were in the warmer 60s. Today is also the runner-up date of the earliest first freeze which occurred in 1984. The earliest first freeze was on September 22, 1995.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:20 and sunrise is at 6:48. Sunset is at 18:38 and twilight ends at 19:06. There's a total of 11 hours, 50 minutes of daylight today and 12 hours, 46 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:21 and sunrise is at 6:49. The moon is waning gibbous. Illumination was 70% at midnight, will be 65% at noon and 60% at midnight tonight. Moonset is at 13:10 this afternoon. Moonrise is at 22:16 tonight. Moonset is at 14:02 tomorrow afternoon. Moonlight time is 14 hours, 54 minutes which is 4 minutes longer than yesterday. The moon is at it's peak duration today.

Columbus Day is in 12 days. -Bernie-