September 3: ORD

Today is September 3rd. It's the 246th day of the year. 119 days remain. It's week 36 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 78 and the normal low is 58. I've calculated the 31-year averages at 80 and 59.

On the hot side, in 1985 the high was 88 with a low of 72. Other hot highs were 91 in 1983, 90 in 1999 and 88 three years ago. The record high of 97 was set in 1953. The record warmest low of 75 occurred in 1973. Over the last 31 years, 26 highs (84%) were: 70s (10) and 80s (16). Two highs were in the warmer 90s. Three highs were in the cooler 60s.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1974 the high was 64 with a low of 46, a cool day. That low of 46 was cooler than the record low and 1974 is the year of the record low. In 1973 the high was 92 with a low of 70, a hot day. 1973 is the year of the record warmest low. In 1971 the high was 87 with a low of 73, a hot day. In 1967 the high was 76 with a cool low of 44, a 32 degree spread. That low of 44 was cooler than the record low. In 1964 the high was a hot 94 with a low of 67, a hot day. In 1960 the high was 96 with a low of 72, another hot day.

More recently, there was a large spread of 31 degrees in 1983 (91/60). There was a small spread of six degrees in 1981 (66/60).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest highs were the three 60s: 66 in 1981, 67 in 1997 and 68 in 1994. The lowest temperatures were the two 40s: 48 in 1982 and 49 in 1987. The record low of 47 was set back in 1974. The record coolest high of 59 occurred way back in 1891. Over the last 31 years, 28 lows (90%) were: 50s (13) and 60s (15). Two lows were in the cooler 40s and one low was in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:52 and sunrise is at 6:21. Sunset is at 19:24 and twilight ends at 19:52. There's a total of 13 hours, 3 minutes of daylight today and 14 hours between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 5:53 and sunrise is at 6:22. The moon reached last quarter two days ago at 12:22 and is waning crescent. Illumination was 34% at midnight, will be 29% at noon and 24% at midnight tonight. Moonrise was at 24 minutes past midnight. Moonset is at 16:09 this afternoon and moonrise is at 1:33 tomorrow morning. Moonset is at 16:53 tomorrow afternoon. Moonlight time is 15 hours, 45 minutes which is 28 minutes longer than yesterday. Moonlight time is at it's peak today.

Labor Day is in three days and Patriot Day is in eight days. -Bernie-