July 22: ORD

Today is July 22nd. It's the 204th day of the year. 162 days remain. It's week 29 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 84 and the normal low is 64. I've calculated the 33-year averages at 83 and 64.

On the hot side, in 1991 (O'Hare's warmest July 22nd) the high was the record high of 101 with a low of 74. The record high of 101 originally occurred in 1934. In 1983 (O'Hare's second warmest July 22nd) the high was the former record high of 100 with a low of 73. O'Hare's second warmest low of 76 degrees occurred in 2002. The record warmest low of 80 degrees occurred in 1972 at Midway. 24 of the past 33 highs (73%) were in the: 70s (13) and 80s (11). O'Hare recorded seven consecutive 70s & 80s highs from 1992 through 1998. Nine highs (27%) were in the hot: 90s (7) and 100s (2). 1972 was O'Hare's third warmest July 22nd as the high was 93 with a low of 79 (O'Hare's warmest low of the date).

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1974 the high was a cool 71 degrees. In 1973 the high was 79 with a low of 72, a seven degree spread. In 1972 the high was 93 with a warm low of 79, a hot day. 1972 had the same temperatures two days in a row (on the 21st & 22nd) and is the year of the record warmest low (80 at Midway). In 1966 the high was 84 with a cold low of 48, a 36 degree spread.

More recently, there was a large spread of 30 degrees in 1984 (93/63) and a small spread of four degrees in 1997 (71/67).

On the cool side, in 2000 (O'Hare's coolest July 22nd) the high was 72 with a low of 53. In 1981 the high was 74 with a low of 55. In 1992 the high was 71 (tied with 1974 and 1997 as O'Hare's coolest highs of the date) with a low of 58. The record low of 49 and record coolest high of 68 were set on the same cool day back in 1947 at Midway. 19 of the last 33 lows (58%) were in the 60s. Seven lows (21%) were in the cold 50s. Seven lows (21%) were in the warm 70s. O'Hare's coldest low of the date was 48 degrees in 1966.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:04 and sunrise is at 5:37. Sunset is at 20:22 and twilight ends at 20:55. There's a total of 14 hours, 45 minutes of daylight today and 15 hours, 51 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 5:05 and sunrise is at 5:38. The moon is waxing crescent. Illumination was 10% at midnight, will be 14% at noon and 18% at midnight tonight. Moonrise is at 9:27 this morning. Moonset is at 21:58 tonight. Moonrise is at 10:35 tomorrow morning. Moonlight time is 12 hours, 31 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. Parent's Day is today.