August 19: ORD

Today is August 19th. It's the 231st day of the year. 134 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 81 and the normal low is 62. I've calculated the 31-year averages at 80 and 62.

On the hot side, in 1983 the high was the record high of 99 with a low of 71. The only other 90s high was 91 in 1980. There were three other lows in the 70s: 72 in 1995, 71 in 1993 and 70 in 1988. The record warmest low of 82 occurred back in 1916. Over the last 31 years, 28 highs (90%) were: 70s (13) and 80s (15). Two highs were in the warmer 90s and one high was in the cooler 60s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1968 the high was 91 with a warm low of 75, a hot day. In 1967 the high was a cool 64 with a low of 57, a seven degree spread. In 1964 the high was 82 with a cool low of 49, a 33 degree spread. That low of 49 is cooler than the record low.

More recently, there were small spreads of four degrees in 1988 (74/70) and six degrees three years ago (68/62).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest temperature was the record low of 51 in 1992. The coolest high was 68 three years ago. You have to go all the way back to 1967 to find the previous sub-70 degree high of 64 degrees. On that day in 1967 we also had 0.52 inches of rain. The record coolest high of 62 was set way back in 1897. The official thermometer was located near Lake Michigan at the time. Over the last 31 years, 27 lows (87%) were: 50s (13) and 60s (14). Four lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:35 and sunrise was at 6:05. Sunset is at 19:48 and twilight ends at 20:18. There's a total of 13 hours, 43 minutes of daylight today and 14 hours, 43 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:36 and sunrise is at 6:06. The moon is waxing gibbous. Illumination was 75% at midnight, will be 79% at noon and 83% at midnight tonight. Moonset was at 1:05 this morning. Moonrise is at 16:54 this afternoon. Moonset is at 2:04 tomorrow morning. Moonlight time is 8 hours, 11 minutes which is 6 minutes longer than yesterday. -Bernie-