August 28: ORD

Today is August 28th. It's the 240th day of the year. 125 days remain. It's week 35 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 81 and the normal low is 61. I've calculated the 32-year averages at 81 and 62.

On the hot side, in 1991 the high was 95 with a low of 71. In 1980 the high was 95 with a low of 69. The other 90s highs were 94 in 1984, 93 in 1990, 92 in 1983, 92 in 2003, 91 in 2007 (our most recent) and 90 in 1999. The other 70s low was 70 in 1999. The record high of 97 was first set in 1953 and tied just two years later in 1955. The record warmest low of 77 was set in 1973. 28 of the past 32 highs (88%) were in the: 70s (12), 80s (8) and 90s (8). Four highs were in the cool 60s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1973 the high was 92 with a warm low of 75, a hot day and year of the record warmest low. In 1967 the high was 78 with a cool low of 47, a 31 degree spread. In 1965 the high was 65 with a low of 42, a cool day and year of the record coolest high. In 1962 the high was 89 with a low of 59, a 30 degree spread.

More recently, there was a large spread of 33 degrees in 2003 (high of 92, low of 59). There were no small spreads of seven degrees or less.

On the cool side, in 1986 the high was 65 with the record low of 42. Four years earlier, in 1982, the high was 66 with a low of 43. The other 60s highs were 68 two years ago (in 2009) and 69 in 1992. The record coolest high of 62 occurred in 1965. The former record coolest high of 63 occurred way back in 1891. 20 of the last 32 lows (63%) were in the 60s. Ten lows (31%) were in the cool: 40s (2) and 50s (8). Two lows (6%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:45 and sunrise is at 6:14. Sunset is at 19:34 and twilight ends at 20:03. There's a total of 13 hours, 20 minutes of daylight today and 14 hours, 18 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 5:46 and sunrise is at 6:15. The moon is new tonight at 22:04. Illumination was 1% at midnight, will be 0% at noon and 0% at midnight tonight. Moonrise is at 5:41 this morning. Moonset is at 19:01 tonight. Moonrise is at 6:57 tomorrow morning. Moonlight time is 13 hours, 20 minutes which is 42 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 eight days. 9/11 Remembrance Day and Grandparents Day are in 13 days.