June 1: ORD

Today is June 1st. It's the 152nd day of the year. 214 days remain. It's week 22 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 75 and the normal low is 53. I've calculated the 33-year averages at 78 and 54.

On the hot side, in 1988 (O'Hare's warmest June 1st) the high was 93 (O'Hare's warmest high of the date) with a low of 60, a 33 degree spread. In 2002 (O'Hare's second warmest June 1st) the high was 92 (O'Hare's second warmest high of the date) with a low of 60, a 32 degree spread. The other warm low was 65 in 1987. The record high of 102 and record warmest low of 74 were set on the same hot day back in 1934 at the University of Chicago. 25 of the past 33 highs (76%) were in the: 70s (12) and 80s (13). There were consecutive 70s & 80s highs as follows: six from 1995 through 2000 and eight from 2004 through last year, 2011. Two highs (6%) were in the hot 90s. Six highs (18%) were in the cool 60s. Our most recent 60s high was 63 in 2003. O'Hare has not recorded a high of 87, 88 or 89 on this day (80s that are significantly above normal). There have been four highs of 85 degrees and three of 86 degrees in the last 33 years. Most recently, the high was 85 degrees two years ago, in 2010 and in 2007. O'Hare's warmest lows of the date are 68 degrees in 1961 and 1970.

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 49, a 31 degree spread. In 1970 the high was 75 with a warm low of 68, a seven degree spread. In 1966 the low was a cold 40 degrees. In 1964 the low was a cold 41 degrees. In 1963 the high was 85 with a low of 55, a 30 degree spread. In 1961 the low was a warm 68 degrees.

More recently, there were additional large spreads of 38 degrees in 1986 (86/48), 34 degrees in 1984 (83/49) and 30 degrees in 2005 (80/50).
 
On the cool side, in 2003 the high was 63 with a low of 38. A decade earlier, in 1993, the high was 64 with the record low of 37. 1993 and 2003 are tied as O'Hare's coolest June 1st days. The other cold low was 41 in 1983. O'Hare's  coolest high of the date is 62 in 1994. The record coolest high of 48 occurred in 1946 at Midway. 25 of the last 33 lows (76%) were in the: 50s (15) and 60s (10). O'Hare recorded eight consecutive 50s & 60s lows from 2004 through last year, 2011. Eight lows (24%) were in the cold: 30s (2) and 40s (6). Our most recent 40s low was 49 in 2001.

The past eight years (2004-2011) have followed the normal pattern of a high in the 70s or 80s and a low in the 50s or 60s. It is interesting to note that our most recent 90s high (92 in 2002) was followed by our most recent 60s high (63 in 2003).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:45 and sunrise is at 5:19. Sunset is at 20:24 and twilight ends at 20:58. There's a total of 15 hours, 5 minutes of daylight today and 16 hours, 13 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 4:45 and sunrise is at 5:19. The moon is waxing gibbous, heading towards the full Strawberry (a.k.a. Rose or Hot) moon in three mornings at 6:12. Illumination was 85% at midnight, will be 89% at noon and 93% at midnight tonight. Moonset was at 2:57 this morning. Moonrise is at 17:23 this afternoon. Moonset is at 3:38 tomorrow morning. Moonlight time is 9 hours, 34 minutes which is 40 minutes shorter than yesterday. 

Spring began on March 12th and runs for 84 days through June 3rd. Warm Spring began on April 13th and runs for 52 days through June 3rd. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 80s and 90s occur infrequently. Flag Day is in 13 days.