August 6: ORD

Today is August 6th. It's the 218th day of the year. 147 days remain. It's week 32 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 83 and the normal low is 64. I've calculated the 32-year averages at 83 and 63.

On the hot side, in 1984 the high was 94 with a low of 71. In 2001 the high was 92 with a low of 70. In 2007 the high was 88 with a low of 74. The other 90s highs were 93 in 1988 and 90 in 1996. The other 70s lows were 72 in 1980, 72 in 1998 and 71 in 1995. The record high of 101 was last reached in 1947 after originally being set back in 1918. The record warmest low of 82 was set back in 1918. The official thermometer was located near Lake Michigan at the time. 19 of the past 32 highs (59%) were in the 80s. Four highs (13%) were in the hot 90s. Nine highs (28%) were in the cool 70s. Our most recent 70s high was 76 in 2004.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1968 the high was 96 with a low of 77, a hot day. In 1964 the high was 85 with a low of 54, a 31 degree spread.

More recently, there were large spreads of 35 degrees in 1988 (93/58) and 30 degrees in 1987 (87/57).

On the cool side, in 1994 the high was 72 with the record low (and only 40s low) of 48. Four years earlier, in 1990, the high was 70 with a low of 54. A year before that, in 1989, the high was 72 with a low of 53. Another cool high was 72 in 1986. The record coolest high of 65 was set way back in 1893. The official thermometer was located near Lake Michigan at the time. 16 of the last 32 lows (50%) were in the 60s. Ten lows (31%) were in the cool: 40s (1) and 50s (9). Six lows (19%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:20 and sunrise is at 5:51. Sunset is at 20:07 and twilight ends at 20:38. There's a total of 14 hours, 16 minutes of daylight today and 15 hours, 18 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 5:21 and sunrise is at 5:52. The moon reaches first quarter today at 6:08. Illumination was 48% at midnight, will be 53% at noon and 59% at midnight tonight. Moonrise is at 14:12 this afternoon. Moonset is at 23:53 tonight. Moonrise is at 15:20 tomorrow afternoon. Moonlight time is 9 hours, 41 minutes which is 30 minutes shorter than yesterday.

Summer began June 4 and runs for 110 days through September 21. High temperatures in this period are usually in the 70s and 80s. Highs in the 60s, 90s and 100s occur infrequently. Labor Day is in 30 days.