August 20: ORD

Today is August 20th. It's the 232nd day of the year. 133 days remain. It's week 34 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 31-year averages at 80 and 61.

On the hot side, in 1980 the high was 93 with a low of 74. That was the lone 90s high of the last 31 years. The two 90s highs prior to 1980 were both very hot: 94 in 1971 and 95 in 1968. In 1968, today was the second of six straight days of 90 degrees or higher (from the 19th through the 24th). Three of these days (today, the 21st and the 23rd) recorded the warmest highs, that of 95 degrees. The record high of 98 was set back in 1947. The record warmest low of 80 occurred back in 1916. Over the last 31 years, 30 highs (97%) were: 70s (15) and 80s (15). One high was in the warmer 90s. The Weather Channel's forecast for today for towns (and direction from ORD) bordering O'Hare calls for the following high temperatures: Des Plaines (N): 91, Bensenville (W/SW): 91, Franklin Park (SE): 91, Elk Grove Village (NW): 90 and Schiller Park (E): 91. So this could be the 2nd 90 of the last 32 years (a small 6% gem). The National Weather Service is predicting a high near 90 for all these locations.

This summer we broke a 55 year old record. In 1955 there was a stretch of 42 consecutive days of highs of at least 80 degrees. This year, from July 2 through August 16, there were 46 consecutive days of highs of at least 80 degrees. The high on August 17 was 79 degrees.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1976 the high was 88 with a low of 57, a 31 degree spread. In 1971 the high was a hot 94. In 1968 the high was a hot 95 with a low of 71, a hot day. In 1962 the high was 91 with a low of 61, a 30 degree spread. In 1959 the high was 91 with a warm low of 74, a hot day.

More recently, there was a small spread of five degrees in 1990 (74/69). There were two large spreads: 32 degrees in 1986 (86/54) and 30 degrees in 1987 (85/55).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest temperature was 49 in 1992. The coolest high was 71 in 1985. The record low of 47 was set in 1950. The record coolest high of 66 occurred in 1940. Over the last 31 years, 29 lows (94%) were: 50s (13) and 60s (16). One low was in the cooler 40s and one was in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:36 and sunrise was at 6:06. Sunset is at 19:47 and twilight ends at 20:16. There's a total of 13 hours, 41 minutes of daylight today and 14 hours, 40 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:37 and sunrise is at 6:07. The moon is waxing gibbous. Illumination was 83% at midnight, will be 86% at noon and 89% at midnight tonight. Moonset is at 2:04 this morning. Moonrise is at 17:34 this afternoon. Moonset is at 3:05 tomorrow morning. Moonlight time is 8 hours, 30 minutes which is 19 minutes longer than yesterday. -Bernie-