August 12: ORD

Today is August 12th. It's the 224th day of the year. 141 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 82 and the normal low is 63. I've calculated the 31-year averages at 80 and 62.

On the hot side, in 1995 the high was 98 with a low of 75. In 1988 the high was 93 with a low of 75. The record high of 101 was set back in 1918. The record warmest low of 78 occurred way back in 1881. Over the last 31 years, 27 highs (87%) were: 70s (12) and 80s (15). Two highs were in the warmer 90s and two highs were in the cooler 60s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1967 the high was 74 with a cool low of 44, a 30 degree spread and cool day. That low of 44 was cooler than the record low. In 1964 the high was a cool 66 with a low of 53, a cool day.

More recently, there were no large spreads of at least 30 degrees or small spreads of up to seven degrees diurnal.

On the cool side, in 2004 the high was the record coolest high of 62 with a low of 49. The previous record coolest high of 64 occurred way back in 1903. The official thermometer was located near Lake Michigan at the time. In 1982 the high was 74 with the record low of 47. In 1992 the high was 67 with a low of 56. Other cool lows were 50 in both 1979 and 1986. Over the last 31 years, 25 lows (81%) were: 50s (9) and 60s (16). Two lows were in the cooler 40s. Four lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:27 and sunrise is at 5:58. Sunset is at 19:58 and civil twilight ends at 20:29. Nautical twilight ends at 21:06 and astronomical twilight ends at 21:47. There's a total of 14 hours of daylight today and 15 hours, 2 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:28 and sunrise is at 5:59. The moon is waxing crescent. Illumination was 7% at midnight, will be 10% at noon and 14% at midnight tonight. Moonrise is at 9:12 this morning. Moonset is at 21:06 tonight. Moonrise is at 10:28 tomorrow morning. Moonlight time is 11 hours, 54 minutes which is 50 minutes shorter than yesterday. -Bernie-