July 10: ORD

Today is July 10th. It's the 191st day of the year. 174 days remain. It's week 28 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 63. I've calculated the 32-year averages at 84 and 63.

On the hot side, in 1989 the high was 101 (a degree off the record) with a low of 73. Five years earlier, in 1984, the high was 99 with a low of 66, a 33 degree spread. The record high of 102 and record warmest low of 80 were set on the same hot day back in 1936. The record high of 102 was originally set way back in 1901. 15 of the past 32 highs (47%) were in the 80s. Nine highs (28%) were in the hot: 90s (8) and 100s (1). Eight highs (25%) were in the cool 70s.

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1976 the high was 97 with a low of 76, a hot day. In 1968 the high was a cool 67 with a low of 53, a cool day. In 1966 the high was a hot 97 degrees. In 1965 the high was 80 with a cool low of 50 (equal to the record), a 30 degree spread. In 1963 the high was 83 with a cold low of 45 (lower than the record), a 38 degree spread. In 1962 the high was 84 with a cool low of 51 (just above the record), a 33 degree spread.

More recently, there were large spreads of 35 degrees in 1981 (91/56) and 31 degrees in 2005 (91/60).

On the cool side, in 1996 the high was 75 with the co-record low of 50. Three years later, in 1999, the high was 74 with a low of 54. Two years prior, in 1997, the high was 78 with the co-record low of 50. Our coolest high was 73 degrees in 2006. The record coolest high of 62 occurred back in 1917. 24 of the last 32 lows (75%) were in the 60s. Seven lows were in the cool 50s and one was in the warm 70s. Our most recent 50s low was 54 in 1999.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:52 and sunrise is at 5:26. Sunset is at 20:31 and twilight ends at 21:05. There's a total of 15 hours, 5 minutes of daylight today and 16 hours, 13 minutes between twilights. We lost no minutes of daylight from yesterday. Tomorrow twilight begins at 4:53 and sunrise is at 5:27. The moon is waxing gibbous, having passed first quarter two mornings ago at 1:29. Illumination was 72% at midnight, will be 77% at noon and 82% at midnight tonight. Moonset is at 1:09 this morning. Moonrise is at 16:21 this afternoon. Moonset is at 1:53 tomorrow morning. Moonlight time is 8 hours, 48 minutes which is 33 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 14 days.