August 14: ORD

Today is August 14th. It's the 226th day of the year. 139 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 81 and 62.

On the hot side, in 1995 the high was 95 with the record warmest low of 79. In 1988 the high was 92 with a very warm low of 75. There were only two other 90s highs: both 90 degrees, in 1983 and a decade later in 1993. The only other 70s low was 72 last year, in 2010. The record high of 99 was set in 1944. 27 of the past 32 highs (84%) were in the: 70s (13) and 80s (14). Four 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 1970 from the 11th through the 17th, highs were at least 85. The warmest was 88 on the 15th. Lows were at least 62 except for 57 on the 17th. In 1969 from the 12th through the 18th, highs were at least 85. The warmest was 88 on the 14th. Lows were at least 68 except for 61 on the 12th. The warmest low was 74 on the 14th. In 1967 the low was a cold 48 degrees which is equal to the day's record low. In 1964 the high was 76 with a cold low of 42, a 34 degree spread and a cool day. That low of 42 was colder than the record low. In 1963 the high was 72 with a cold low of 48, a cool day. That low of 48 was also equal to the day's record low. In 1962 the high was a cool 70 degrees. In 1959 the low was a warm 75 degrees.

More recently, there was a large spread of 33 degrees in 1984 (84/51).

On the cool side, in 2004 the high was 70 with a low of 50. In 1992 the high was 67 (our only 60s high) with a low of 56. In 1979 the high was 70 with a low of 53. Other cool lows were 51 in 1984 and 52 in 1990. The record low of 48 was set at Midway in 1964. The record coolest high of 65 occurred way back in 1885. The official thermometer was located near Lake Michigan at the time. 29 of the last 32 lows (91%) were in the: 50s (12) and 60s (17). Three lows were in the warmer 70s.

As you can see, this is a day dominated by highs in the 70s or 80s and lows in the 50s or 60s. There's an ongoing long stretch of such highs. This is 15 years from 1996 through last year, 2010. There were two long stretches of such occurrences with the lows. The first was nine years from 1979 through 1987. The second was 14 years from 1996 through 2009.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:29 and sunrise is at 5:59. Sunset is at 19:56 and twilight ends at 20:26. There's a total of 13 hours, 57 minutes of daylight today and 14 hours, 57 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 5:30 and sunrise is at 6:00. The moon is waning gibbous, having passed full yesterday at 13:57 as the full Sturgeon moon. Other names for this moon are Green Corn and Grain. Illumination was 100% at midnight, will be 99% at noon and 98% at midnight tonight. Moonset is at 6:56 this morning. Moonrise is at 20:03 tonight. Moonset is at 7:57 tomorrow morning. Moonlight time is 10 hours, 53 minutes which is 38 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 22 days.