August 2: ORD

Today is August 2nd. It's the 214th day of the year. 151 days remain. It's week 31 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 85 and 64.

On the hot side, in 1988 the high was the former record high of 100 with the record warmest low of 79. In 2006 the high was 97 with a low of 77. In 1987 the high was 96 with a low of 74. In 1991 the high was the record high of 101 with a low of 67, a 34 degree spread. 17 of the past 32 highs (53%) were in the 80s. Eight highs (25%) were in the hot: 90s (6) and 100s (2). Seven highs (22%) were in the cool 70s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1975 the high was 78 with a low of 73, a five degree spread. In 1966 the high was 71 with a low of 52, a cool day. In 1965 the high was 73 with a cold low of 49, a cool day. That low of 49 is colder than the record low. In 1964 the high was 96 with a low of 76, a hot day. In 1962 the high was 83 with a low of 53, a 30 degree spread.

More recently, there were no other large or small spreads.

On the cool side, in 1985 the high was 77 with the record low of 51. In 1994 the high was 77 with a low of 56. Another of our coolest highs of 77 occurred in 1996. The record coolest high of 63 occurred back in 1927. The official thermometer was located near Lake Michigan at the time. 17 of the last 32 lows (53%) were in the 60s. Nine lows (28%) were in the cool 50s. 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 5:15 and sunrise is at 5:47. Sunset is at 20:12 and twilight ends at 20:43. There's a total of 14 hours, 25 minutes of daylight today and 15 hours, 28 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 5:16 and sunrise is at 5:48. The moon is waxing crescent, having become new three days ago at 13:40. Illumination was 8% at midnight, will be 12% at noon and 16% at midnight tonight. Moonrise is at 9:19 this morning. Moonset is at 21:32 tonight. Moonrise is at 10:33 tomorrow morning. Moonlight time is 12 hours, 13 minutes which is 44 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 34 days.