July 25: ORD

Today is July 25th. It's the 206th day of the year. 159 days remain. It's week 30 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 64. I've calculated the 32-year averages at 84 and 65.

On the hot side, in 1987 the high was 95 with a low of 74. In 1999 the high was 96 with a low of 73. The other 90s highs were 92 in 1995 and 90 in 2006. Another warm low was 73 in 2006. The record high of 101 was set in 1940. The record warmest low of 77 occurred way back in 1892. 22 of the past 32 highs (69%) were in the 80s. Four highs (12%) were in the hot 90s. Six highs (19%) were in the cool 70s.

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1970 today and tomorrow (25th & 26th) the temperatures were the same: a high of 89 with a low of 71. In 1965 the high was 88 with a low of 58, a 30 degree spread.

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

On the cool side, in 2004 the high was 73, our coolest high, with a low of 60. In 1991 the high was 77 with a low of 58. Our coolest lows were 57 in both 1998 and 2000. The record low of 53 was set a century ago, in 1911. The record coolest high of 64 occurred back in 1920. 20 of the last 32 lows (62%) were in the 60s. Four lows (13%) were in the cool 50s. Eight lows (25%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:07 and sunrise is at 5:39. Sunset is at 20:20 and twilight ends at 20:53. There's a total of 14 hours, 41 minutes of daylight today and 15 hours, 46 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 5:08 and sunrise is at 5:40. The moon is waning crescent, having reached last quarter two days ago at 0:02. Illumination was 31% at midnight, will be 26% at noon and 22% at midnight tonight. Moonrise is at 0:47 this morning. Moonset is at 16:07 this afternoon. Moonrise is at 1:31 tomorrow morning. Moonlight time is 15 hours, 20 minutes which is 22 minutes longer 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 42 days.