August 15: ORD

Today is August 15th. It's the 227th day of the year. 138 days remain. It's week 33 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 82 and 63.

On the hot side, in 1988 the high was 94 with record warmest low of 74. There were three other 90s highs: 92 in 2000, 90 in 1983 and 90 in 1987. There were six other lows in the 70s, all of them in the low 70s. The record high of 98 was set in 1944. Over the last 31 years, 26 highs (84%) were: 70s (10) and 80s (16). Four highs were in the warmer 90s and one high was 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 1964 the high was 78 with a low of 41, a 37 degree spread and cool day. That low of 41 is cooler than the record low. In 1963 the low was a cool 50.

More recently, there was a large spread of 33 degrees in 1984 (87/54).

On the cool side, in 1979 the high was 69 with a low of 46. That low of 46 is cooler than the record low. The record low of 48 was set in 2004. The former record low of 51 was set at Midway in 1964. There was only one lower 70s high. This was 71 in 1992. The record coolest high of 64 was set way back in 1894. The official thermometer was located near Lake Michigan at the time. Over the last 31 years, 17 lows were 60s. Seven lows were: 40s (2) and 50s (5). Seven lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:30 and sunrise was at 6:01. Sunset is at 19:54 and civil twilight ends at 20:24. Nautical twilight ends at 21:01 and astronomical twilight ends at 21:41. There's a total of 13 hours, 53 minutes of daylight today and 14 hours, 54 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:32 and sunrise is at 6:02. The moon is waxing crescent and reaches first quarter tomorrow at 13:14. Illumination was 34% at midnight, will be 39% at noon and 45% at midnight tonight. Moonrise is at 12:56 this afternoon. Moonset is at 22:42 tonight. Moonrise is at 14:06 tomorrow afternoon. Moonlight time is 9 hours, 46 minutes which is 38 minutes shorter than yesterday. -Bernie-