July 12: ORD

Today is July 12th. It's the 193rd day of the year. 172 days remain. It's week 28 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 84 and the normal low is 63. I've calculated the 32-year averages at 84 and 64.

On the hot side, in 1995 the high was the record high of 97 (also our most recent 90s high) with a low of 73. The record high of 97 originally occurred in 1952 and was tied in 1954. In 1981 the high was 94 with a low of 73. The other 90s highs were 94 in 1980, 92 in 1979, 91 in 1994 and 90 in 1987. The other warm 70s lows were 72 in 2005 (our most recent 70s low) and 70 in 1994. The record warmest low of 79 occurred back in 1921. 22 of the last 32 highs (69%) were in the 80s. Most of our 80s highs occurred in three streaks of 80s highs. The first was five years from 1982 to 1986. The second was six years from 1996 to 2001. The third is an ongoing eight years, from 2003 to 2010. Six highs (19%) were in the hot 90s and four highs (12%) were in the cool 70s. Our most recent 70s high was 79 in 2002.

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1973 the high was 90 with a low of 58, a 32 degree spread. In 1972 the low was a warm 75 degrees. In 1968 the high was 86 with a low of 56, a 30 degree spread. In 1965 the high was 83 with a low of 52 (cooler than the record low), a 31 degree spread. In 1964 the high was a cool 69 with a low of 52 (cooler than the record low), a cool day.

More recently, there were no small spreads (7 degrees or less) or large spreads (30 degrees or more).

On the cool side, in 1990 the high was 73 (our coolest high) with a low of 59. In 1999 the high was 82 with the record low of 53. The former record low was 55 in 1975. The record coolest high of 65 occurred in 1940. 19 of the last 32 lows (59%) were in the 60s. Nine lows (28%) were in the cool 50s. Four lows (13%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:54 and sunrise is at 5:28. Sunset is at 20:30 and twilight ends at 21:03. There's a total of 15 hours, 2 minutes of daylight today and 16 hours, 9 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 4:55 and sunrise is at 5:29. The moon is waxing gibbous. Illumination was 89% at midnight, will be 93% at noon and 95% at midnight tonight. Moonset is at 2:45 this morning. Moonrise is at 18:28 tonight. Moonset is at 3:44 tomorrow morning. Moonlight time is 8 hours, 17 minutes which is eight minutes shorter than yesterday. Moonlight is at it's shortest duration today.

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. Parent's Day is in 12 days.