August 27: ORD

Today is August 27th. It's the 239th day of the year. 126 days remain. It's week 35 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 79 and the normal low is 60. I've calculated the 31-year averages at 81 and 64.

On the hot side, in 1990 the high was 93 with a low of 72. Three years later, in 1993, the high was 94 with a low of 70. The other 90s highs were 92 in 1991, 91 in 1980 and 90 in 1984. The other 70s lows were 71 in 1980, 71 in 2006 and 70 in 1991. The record high of 97 and record warmest low of 77 were set on the same day in 1973. Over the last 31 years, 15 highs were 80s. Five highs were in the warmer 90s. 11 highs were in the cooler: 60s (5) and 70s (6).

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: in 1977 the high was 92 with a low of 78, a hot day. In 1976 the high was 95 with a low of 74, a hot day. In 1973 the high was 95 with a low of 75, a hot day. 1973 was the year that the records were set at Midway Airport. In 1968 the high was a cool 67 with a low of 50, a cool day. In 1967 the high was a cool 64. In 1964 the high was 85 with a low of 55, a 30 degree spread. In 1962 the high was 88 with a low of 51, a 37 degree spread. In 1961 the high was a hot 93. In 1959 the low was a warm 73.

More recently, there was a small spread of five degrees in 1987 (66/61) and six degrees last year (67/61).

On the cool side, in 1986 the high was 67 with a low of 48. The coolest temperature was the record low of 47 degrees in 1982. The other cool highs were 63 in 1992, 66 in 1987 and 67 last year. The record coolest high of 61 occurred way back in 1915. Over the last 31 years, 22 lows were in the 60s. Four lows were in the cooler: 40s (2) and 50s (2). Five lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:44 and sunrise was at 6:13. Sunset is at 19:35 and twilight ends at 20:05. There's a total of 13 hours, 22 minutes of daylight today and 14 hours, 21 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:45 and sunrise is at 6:14. The moon reached full three days ago as the full Sturgeon or Grain moon at 12:05, just after noon and is waning gibbous today. Illumination was 94% at midnight, will be 92% at noon and 89% at midnight tonight. Moonset was at 9:08 this morning and moonrise is at 20:29 tonight. Moonset is at 10:09 tomorrow morning. Moonlight time is 12 hours, 39 minutes which is 38 minutes longer than yesterday. -Bernie-