June 28: ORD

Today is June 28th. It's the 180th day of the year. 186 days remain. It's week 26 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 83 and the normal low is 62. I've calculated the 33-year averages at 83 and 61.

On the hot side, in 2005 (O'Hare's second warmest June 28th) the high was 94 with a low of 76 (O'Hare's warmest low of the date). In 1991 the high was 89 with a low of 70. The record high of 101 was originally set in 1952 and tied in 1971, both at Midway. The record warmest low of 81 occurred back in 1913, at a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 33 highs (67%) were in the 80s. Two highs (6%) were in the hot 90s. Nine highs (27%) were in the cool: 60s (1) and 70s (8). O'Hare's lone 60s high was 69. It occurred on the coolest day of the past 33 years in 2000. O'Hare's warmest June 28th was in 1971 as the high was 97 (O'Hare's hottest high of the date) with a low of 75.

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1973 the high was a cool 70 degrees. In 1971 the high was 97 with a low of 75, a hot day and year of the record high (101 at Midway). In 1964 the high was 91 with a low of 61, a 30 degree spread. In 1962 the high was 90 with a low of 57, a 33 degree spread. In 1959 the low was a warm 78 degrees.

More recently, there was a small spread of seven degrees in 1983 (70/63). The other spreads were large: 30 degrees in 1996 (92/62) and 30 degrees in 1988 (88/58).

On the cool side, in 2000 (O'Hare's coolest June 28th) the high was 69 (O'Hare's only 60s high and coolest high of the date) with a low of 55. In 1992 the high was 82 with the record low of 44 (O'Hare's only 40s low of the date), a spread of 38 degrees. The other cool high of 70 occurred in 1983. The high was also 70 in 1973. These highs of 70 are O'Hare's second coolest of the date. The record coolest high of 58 occurred way back in 1902, at a time when the official readings were taken adjacent to Lake Michigan. 21 of the last 33 lows (64%) were in the 60s. O'Hare recorded six consecutive 60s lows from 1994 through 1999. Ten lows (30%) were in the cool: 40s (1) and 50s (9). Two lows (6%) were in the warm 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:45 and sunrise is at 5:20. Sunset is at 20:34 and twilight ends at 21:08. There's a total of 15 hours, 14 minutes of daylight today and 16 hours, 23 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 4:45 and sunrise is at 5:20. The moon is waxing gibbous, having reached first quarter two nights ago at 22:30. Illumination was 63% at midnight, will be 68% at noon and 73% at midnight tonight. Moonset was at 0:56 this morning. Moonrise is at 15:04 this afternoon. Moonset is at 1:33 tomorrow morning. Moonlight time is 9 hours, 52 minutes which is 39 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 six days.