June 22: ORD

Today is June 22nd. It's the 174th day of the year. 192 days remain. It's week 25 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 82 and the normal low is 60. I've calculated the 33-year averages at 82 and 60.

On the hot side, in 1988 (O'Hare's hottest June 22nd) the high was the record high of 97 with a low of 66, a 31 degree spread. In 1995 the high was 93 with a low of 69 (O'Hare's co-warmest low of the date). 1988 and 1995 were two of our hottest summers. The other co-warmest low of 69 occurred two years ago in 2010. The record warmest low of 76 occurred back in 1923, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the past 33 highs (73%) were in the: 70s (9) and 80s (15). O'Hare recorded nine consecutive 70s & 80s highs from 2003 through 2011. Five highs (15%) were in the hot 90s. Our most recent 90s high was 92 in 2002. Four (12%) were in the cool 60s. 

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1974 the high was a cool 65 with a low of 52, a cool day. In 1972 the high was a cool 67 with a low of 49, a cool day. In 1969 the high was a cool 66 with a low of 59, a seven degree spread. In 1965 the high was 88 with a low of 52, a 36 degree spread. In 1963 the high was 77 with a cold low of 36, a 41 degree spread and cool day. That low of 36 was colder than the official low. In 1961, the temps (high of 82, low of 60) matched our current normals. In 1959 the high was a cool 70 degrees.

More recently, there were three additional large spreads: 31 degrees in 1993 (87/56), 31 degrees in 2003 (85/54) and 30 degrees in 1994 (88/58). There was a small spread of seven degrees in 1991 (67/60).

On the cool side, in 1992 (O'Hare's coolest June 22nd) the high was 65 (O'Hare's coolest high of the date along with 1974) with a low of 41. A decade earlier, in 1982, the high was 69 with a low of 46. The other cool highs were 67 in 1991 and 69 in 2001. The record low of 40 was set way back in 1875. The record coolest high of 55 occurred way back in 1881. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 31 of the last 33 lows (94%) were in the: 50s (12) and 60s (19). Two lows were in the cool 40s. O'Hare's coldest low of 36 occurred in 1963. This low is colder than the current record low of 40 set in 1875.

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 20:34 and twilight ends at 21:08. There's a total of 15 hours, 17 minutes of daylight today and 16 hours, 25 minutes between twilights. We gained a minute of daylight from yesterday. Today is the longest day of the year. Tomorrow twilight begins at 4:43 and sunrise is at 5:18. The moon is waxing crescent. Illumination was 7% at midnight, will be 10% at noon and 13% at midnight tonight. Moonrise was at 8:20 this morning. Moonset is at 22:26 tonight. Moonrise is at 9:24 tomorrow morning. Moonlight time is 14 hours, 6 minutes which is 30 minutes shorter 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. Independence Day is in 12 days.