June 7: ORD

Today is June 7th. It's the 159th day of the year. 207 days remain. It's week 23 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. Before this, the official site of record was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 77 and the normal low is 55. I've calculated the 33-year averages at 81 and 57.

On the hot side, last year, in 2011 (O'Hare's hottest June 7th), the high was 96 (O'Hare's hottest high of the date) with a low of 75 (O'Hare's warmest low of the date). In 2007 the high was 91 with a low of 71. In 1999 the high was 88 with a low of 73 (with 1968, O'Hare's second warmest low of the date). In 1988 the high was 94 (O'Hare's second warmest high of the date) with a low of 65. The year prior, 1987, saw a high of 89 with a low of 67. The other hot highs were 92 in 1982, 1995 and 2005. The other warm lows were 69 in 1979 and 2008. The record high of 100 and record warmest low of 78 were set on the same hot day back in 1933 at the University of Chicago. 23 of the past 33 highs (70%) were in the: 70s (9) and 80s (14). Six highs (18%) were in the hot 90s. Four highs (12%) were in the cool 60s. O'Hare's second hottest June 7th was in 1968 as the high was 91 with a low of 73 (with 1999, O'Hare's second warmest low of the date). The other pre-1979 hot highs are 92 in 1959 and 91 in 1963.

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1972 the high was 80 with a low of 50, a 30 degree spread. In 1969 the high was a cool 64 degrees. In 1968 the high was 91 with a low of 73, a hot day. In 1967 the high was 76 with a warm low of 69, a seven degree spread. In 1963 the high was 91 with a low of 68, a hot day. In 1960 the high was a cool 64 degrees. In 1959 the high was a hot 92 with a low of 64, a hot day.

More recently, there were large spreads of: 41 degrees in 1995 (92/51), 37 degrees in 1985 (83/46), 32 degrees in 1981 (86/54), 31 degrees in 2005 (92/61), 30 degrees in 1982 (92/62) and 30 degrees in 1994 (83/53).

On the cool side, in 1996 (O'Hare's coolest June 7th) the high was 60 (O'Hare's coolest high of the date) with a low of 48. Two years later, in 1998, the high was 70 with a low of 45 (O'Hare's coldest low of the date). The other cool high was 62 in 1997. All four of the cool 60s highs occurred between 1993 and 2001. The record low of 44 and record coolest high of 50 were set on the same cool day back in 1913, at a time when the official readings were taken adjacent to Lake Michigan. The record low of 44 was originally set way back in 1894. 25 of the last 33 lows (76%) were in the: 50s (15) and 60s (10). O'Hare recorded consecutive lows in the 50s & 60s as follows: ten from 1986 through 1995 and six from 2001 through 2006. Five lows (15%) were in the cool 40s. Our most recent 40s low was 49 in 2000. Three lows (9%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:43 and sunrise is at 5:17. Sunset is at 20:28 and twilight ends at 21:02. There's a total of 15 hours, 11 minutes of daylight today and 16 hours, 19 minutes between twilights. We gained a minutes of daylight from yesterday. Tomorrow twilight begins at 4:43 and sunrise is at 5:17. The moon is waning gibbous, having passed the full Strawberry (a.k.a. Rose or Hot) moon three mornings ago at 6:12. Illumination was 89% at midnight, will be 85% at noon and 81% at midnight tonight. Moonset was at 8:51 this morning. Moonrise is at 23:14 tonight. Moonset is at 10:00 tomorrow morning. Moonlight time is 9 hours, 37 minutes which is 33 minutes longer than yesterday. 

Summer begins three days ago, on June 4th and runs for 110 days through September 21st. High temperatures in this period are usually in the 70s and 80s. Highs in the 90s and 100s occur infrequently. Flag Day is in seven days.