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 31-year averages at 83 and 64.

On the hot side, in 2001 the high was 95 with a low of 75. There were several other highs in the 90s, the hottest were in the mid 90s (94 in 1988 and 93 in 1979). The other warm lows (in the mid 70s) were 75 in 1979, 74 in 1996 and 73 in 1995. The record high of 99 and record warmest low of 79 were set on the same day back in 1918. The official thermometer was located near Lake Michigan at the time. Little difference in the highs over the last 31 years: the 80s have 12, the cooler 70s have ten and the warmer 90s have nine.

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. 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 2005 (89/58), 31 degrees in 1988 (94/63) 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, there were no days of a mean of at least 11.5 degrees below normal. 1989 was 11 degrees below normal as the high was just 72 with a low of 52. The record low of 50 occurred twice, in 1990 and four years later in 1994. The record coolest high of 65 was set way back in 1903. The official thermometer was located near Lake Michigan at the time. Little difference in the lows over the last 31 years: the 60s have 13, the cooler 50s have nine and the warmer 70s have nine.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:21 and sunrise was at 5:52. Sunset is at 20:05 and civil twilight ends at 20:36. Nautical twilight ends at 21:14 and astronomical twilight ends at 21:56. There's a total of 14 hours, 13 minutes of daylight today and 15 hours, 15 minutes between twilights. We are losing about two minutes of daylight a day. Tomorrow twilight begins at 5:22 and sunrise is at 5:53. The moon is waning crescent. Illumination was 12% at midnight, will be 8% at noon and 5% at midnight tonight. Moonrise was at 2:42 this morning. Moonset was at 18:20 this afternoon. Moonrise is at 3:57 tomorrow morning. Moonlight time is 15 hours, 38 minutes which is 16 minutes shorter than yesterday. -Bernie-