July 7: ORD

Today is July 7th. It's the 188th day of the year. 177 days remain. It's week 27 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 83 and the normal low is 62. I've calculated the 32-year averages at 85 and 62.

On the hot side, in 1988 the high was 97 with a low of 71. Last year, in 2010, the high was 93 with a low of 71. In 1980 the high was the record high of 102. The other mid 90s highs were 94 in 1991 and 93 in 1981. Our warmest low was 73 in 1994. The record warmest low of 78 occurred way back in 1876. 15 of the past 32 highs (47%) were in the 80s. Eight highs (25%) were in the hot: 90s (7) and 100s (1). Nine highs (28%) were in the cool: 60s (1) and 70s (8).

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1969 the high was a cool 65 with a low of 60, a five degree spread. In 1961 the high was a cool 70 with a low of 53, a cool day. In 1959 the high was 87 with a low of 56, a 31 degree spread.

More recently, there were large spreads of: 43 degrees in 1980 (102/59), 36 degrees in 1981 (93/57), 30 degrees in 1979 (85/55) and 30 degrees in 1985 (88/58).

On the cool side, in 1984 the high was 74 with a low of 47. A year earlier, in 1983, the high was 79 with the record low of 45. Our coolest high (and only 60s high) was 69 in 2004. The record coolest high of 62 occurred back in 1904. 25 of the last 32 lows (78%) were in the: 50s (10) and 60s (15). Two lows were in the cool 40s (in 1983 & 1984). Five lows were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:50 and sunrise is at 5:24. Sunset is at 20:32 and twilight ends at 21:06. There's a total of 15 hours, 8 minutes of daylight today and 16 hours, 16 minutes between twilights. We lost no minutes of daylight from yesterday. Tomorrow twilight begins at 4:51 and sunrise is at 5:25. The moon is waxing crescent. Illumination was 38% at midnight, will be 44% at noon and 50% at midnight tonight. Moonrise is at 12:44 this afternoon. Moonset is at 23:58 tonight. Moonrise is at 13:57 tomorrow afternoon. Moonlight time is 11 hours, 14 minutes which is 42 minutes shorter than yesterday.

Summer began June 4 and runs for 110 days through September 21. High temperatures in this period are usually in the 70s and 80s. Highs in the 60s, 90s and 100s occur infrequently. Parent's Day is in 17 days.