August 30: ORD

Today is August 30th. It's the 242nd day of the year. 123 days remain. It's week 35 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 79 and the normal low is 59. I've calculated the 31-year averages at 80 and 61.

On the hot side, in 1995 the high was 92 with a low of 74. The other 90s high was 90 in 1993. The other 70s lows were 72 in 1983 and 71 (1980, 1991 and 2000). The record high of 96 was set in 1953. The record warmest low of 76 occurred way back in 1881. Over the last 31 years, 26 highs (84%) were: 70s (11) and 80s (15). Two highs were in the warmer 90s and three highs were in the cooler 60s (66 last year, 67 in 1994 and 69 in 1999).

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 79 with a low of 49, a 30 degree spread. In 1973 the low was a warm 71. In 1970 the high was a hot 91. In 1969 the high was 90 with a warm low of 71, a hot day. In 1967 the high was a cool 67. In 1965 the high was a cool 64. In 1962 the high was 92 with a low of 62, a 30 degree spread. In 1961 the high was a hot 91. In 1959 the temperatures for yesterday (the 29th) and today (the 30th) were the same: a high of 86 with a low of 69.

More recently, there was a large spread of 31 degrees two years ago (87/51) and a small spread of six degrees in 1994 (67/61).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. Last year stands out as the coolest day as the high was the coolest of the last 31 years at 66 degrees and the low was 51. There were two lows in the 40s (48 in 1986 and 49 two years later in 1988). The record low of 47 was set in 1946. The record coolest high of 58 occurred way back in 1915. Over the last 31 years, 24 lows (77%) were in the: 50s (13) and 60s (11). Two lows were in the cooler 40s and five lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:48 and sunrise is at 6:17. Sunset is at 19:31 and twilight ends at 19:59. There's a total of 13 hours, 14 minutes of daylight today and 14 hours, 11 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:49 and sunrise is at 6:18. The moon is waning gibbous. Illumination was 74% at midnight, will be 70% at noon and 65% at midnight tonight. Moonset is at 12:14 this afternoon and moonrise is at 21:55 tonight. Moonset is at 13:18 tomorrow afternoon. Moonlight time is 14 hours, 19 minutes which is 30 minutes longer than yesterday.

Labor Day is in seven days. -Bernie-