June 9: ORD

Today is June 9th. It's the 161st day of the year. 205 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 78 and the normal low is 56. I've calculated the 33-year averages at 76 and 56.

On the hot side, in 1999 the high was 90 with a low of 67. A year later, in 2000, the high was 87 with a low of 67. The other warm low was 70 in 1984. The record high of 98 was set back in 1911. The record warmest low of 77 occurred back in 1914. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 32 of the past 33 highs (97%) were in the: 60s (10), 70s (10) and 80s (12). One high was in the hot 90s. O'Hare's warmest June 9th was in 1959 as the high was 90 with a low of 71 (O'Hare's warmest low of the date). The second warmest was in 1964 as the high was 91 with a low of 69. The third warmest was in 1968 as the high was 93 (O'Hare's hottest high of the date) with a low of 65.
 
In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1978 the high was 76 with a cold low of 44, a 32 degree spread. In 1976 the high was hot 90 degrees. In 1969 the low was a cold 43 degrees. In 1968 the high was a hot 93 with a low of 65, a hot day. In 1967 the low was a warm 70 degrees. In 1966 the high was a cool 61 with a low of 48, a cool day. In 1964 the high was 91 with a low of 69, a hot day. In 1963 the high was a hot 90 degrees. In 1959 the high was 90 with a low of 71, a hot day.

More recently, there were small spreads of six degrees in 1996 (60/54) and six degrees in 1998 (64/58). The large spreads were: 33 degrees in 1994 (73/40), 31 degrees in 2001 (81/50), 31 degrees in 2002 (87/56) and 30 degrees in 1991 (86/56).

On the cool side, in 1988 the high was 63 with a low of 49. In 1980 the high was 69 with a low of 43. The other cold low was the record low of 40 in 1994 (the former record low was 42 in 1977 at Midway). The other cool highs were 60 in 1996 (O'Hare's coolest high of the date), 64 in 1998, 66 in 1987 and 66 in 1989.  The record coolest high of 54 occurred back in 1915, at a time when the official readings were taken adjacent to Lake Michigan. 26 of the last 32 lows (79%) were in the: 50s (16) and 60s (10). O'Hare recorded 14 consecutive 50s & 60s lows from 1998 through last year, 2011. Six lows (18%) were in the cool 40s. Our most recent 40s low was 48 in 1997. One low (3%) was in the warm 70s. O'Hare's coolest June 9th was in 1966 as the high was 61 with a low of 48.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:42 and sunrise is at 5:17. Sunset is at 20:29 and twilight ends at 21:03. There's a total of 15 hours, 12 minutes of daylight today and 16 hours, 21 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 4:42 and sunrise is at 5:17. The moon is waning gibbous, heading towards last quarter in two days at 5:41. Illumination was 72% at midnight, will be 67% at noon and 62% at midnight tonight. Moonset was at 11:07 this morning. Moonrise is at 0:16 tomorrow morning. Moonset is at 12:11 tomorrow afternoon. Moonlight time is 11 hours, 7 minutes which is 54 minutes longer than yesterday. 

Summer began 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 five days.