August 16: ORD

Today is August 16th. It's the 228th day of the year. 137 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 32-year averages at 83 and 62.

On the hot side, in 1988 the high was the co-record high of 98 with a low of 73. Five years earlier, in 1983, the high was the other co-record high of 98 with a low of 71. In 1995 the high was 94 with a low of 73. In 2003 the high was 92 (our most recent 90s high) with a low of 73. The only other 70s low was 70 two years ago in 2009. The record warmest low of 78 occurred back in 1913. 24 of the past 32 highs (75%) were in the: 70s (9) and 80s (15). Seven highs were in the hot 90s and one was 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 1976 the low was a cold 49 degrees, just above the record low. In 1968 the high was a hot 94 degrees. In 1964 the high was 83 with a cold low of 46, a 37 degree spread. That low of 46 was colder than the record low. In 1963 the high was 81 with a cool low of 51, a 30 degree spread.

More recently, there was a large spread of 30 degrees in 2004 (78/48) and a small spread of five degrees in 2001 (70/65).

On the cool side, in 1979 the high was 72 with a low of 45, a low colder than the record low. The record low of 48 was set in 2004. The former record low of 49 was set at Midway in 1976. In 1992 the high was 74 with a low of 50. In 1980 the high was 66 (our only 60s high and just a degree above the record) with a low of 58. The other cool highs were 70 in 1981 and 70 again two decades later in 2001. The record coolest high of 65 occurred way back in 1902. The official thermometer was located near Lake Michigan at the time. 25 of the last 32 lows (78%) were in the: 50s (9) and 60s (16). Two lows were in the cold 40s. Five lows were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:31 and sunrise is at 6:02. Sunset is at 19:53 and twilight ends at 20:23. There's a total of 13 hours, 51 minutes of daylight today and 14 hours, 52 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 5:33 and sunrise is at 6:03. The moon is waning gibbous, having passed full three days ago at 13:57 as the full Sturgeon moon. Other names for this moon are Green Corn and Grain. Illumination was 94% at midnight, will be 92% at noon and 89% at midnight tonight. Moonset is at 8:57 this morning. Moonrise is at 20:51 tonight. Moonset is at 9:57 tomorrow morning. Moonlight time is 12 hours, 6 minutes which is 36 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 20 days.