August 23: ORD

Today is August 23rd. It's the 235th day of the year. 130 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 80 and the normal low is 61. I've calculated the 31-year averages at 81 and 62.

On the hot side, there were no days of a mean of at least 11.5 degrees above normal. In 1998 the high was 90 with a low of 71. In 1993 the high was 91 with a low of 69. Those highs were the only ones in the 90s over the past 31 years and that low of 71 was the only 70s low. The record high of 97 was set in 1947. The record warmest low of 76 occurred in 1968. Over the last 31 years, 29 highs (94%) were: 70s (14) and 80s (15). Two highs were in the warmer 90s.

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 1975 the high was 92 with a low of 74, a hot day. In 1973 the high was a cool 67 with a low of 63, a four degree spread. In 1972 the high was 75 with a low of 71, a four degree spread. In 1969 the high was 86 with a low of 53, a 33 degree spread. In 1968 the high was 95 with a low of 77, a hot day and year of the record warmest low. In 1965 the low was a cool 47, cooler than the record low. In 1964 the high was a cool 68. In 1962 the high was a hot 94. In 1961 the high was a cool 68. In 1959 the low was a warm 73.

More recently, there was a small spread of five degrees in 2001 (74/69).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest temperatures were lows of 54 degrees, happening in 1987 and repeating a decade later in 1997. The record low of 51 was set way back in 1888. The coolest high of 73 first occurred in 1987 and again in 2005. The record coolest high of 62 occurred way back in 1890. The official thermometer was located near Lake Michigan at the time. Over the last 31 years, 20 lows were in the 60s. Ten lows were in the cooler 50s. One low was in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:40 and sunrise was at 6:09. Sunset is at 19:42 and twilight ends at 20:11. There's a total of 13 hours, 33 minutes of daylight today and 14 hours, 31 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:41 and sunrise is at 6:10. The moon is waxing gibbous, heading towards the full Sturgeon or Grain moon tomorrow at 12:05. Illumination was 98% at midnight, will be 99% at noon and 100% at midnight tonight. Moonset was at 5:08 this morning. Moonrise is at 19:01 tonight. Moonset is at 6:09 tomorrow morning. Moonlight time is 10 hours, 7 minutes which is 36 minutes longer than yesterday. -Bernie-