August 7: ORD

Today is August 7th. It's the 219th day of the year. 146 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 64.

On the hot side, in 2001 the high was 95 with a low of 75. In 1979 the high was 93 with a low of 75. Another hot high was 94 in 1988. The other warm lows (in the mid 70s) were 74 in 1996 and 73 in 1995. The record high of 99 and record warmest low of 79 were set on the same hot day back in 1918. The official thermometer was located near Lake Michigan at the time. 23 of the past 32 highs (72%) were in the: 70s (10) and 80s (13). Nine highs (28%) were in the hot 90s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1972 the high was a cool 68 degrees. In 1966 the high was 86 with a low of 56, a 30 degree spread. In 1964 the high was 92 with a low of 56, a 36 degree spread.

More recently, there were large spreads of 31 degrees in 1988 (94/63), 31 degrees in 2005 (89/58) and 30 degrees in 1994 (80/50). The small spreads were six degrees in 1999 (75/69) and seven degrees in 1998 (78/71).

On the cool side, in 1989 the high was 72 with a low of 52. Four years later, in 1993, the high was 76 with a low of 53. Three years prior, in 1990, the high was 79 with the co-record low of 50. The record low of 50 was most recently set in 1994. Another cool low was 53 in 2004. The record coolest high of 65 was set way back in 1903. The official thermometer was located near Lake Michigan at the time. 14 of the last 32 lows (44%) were in the 60s. Nine lows (28%) were in the cool 50s and another nine lows (28%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:21 and sunrise is at 5:52. Sunset is at 20:05 and twilight ends at 20:36. There's a total of 14 hours, 13 minutes of daylight today and 15 hours, 15 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 5:22 and sunrise is at 5:53. The moon is waxing gibbous, having reached first quarter yesterday at 6:08. Illumination was 59% at midnight, will be 64% at noon and 70% at midnight tonight. Moonrise is at 15:20 this afternoon. Moonset is at 0:42 tomorrow morning. Moonrise is at 16:21 tomorrow afternoon. Moonlight time is 8 hours, 40 minutes which is 61 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 29 days.