June 20: ORD

Today is June 20th. It's the 171st day of the year. 194 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.

According to the National Climatic Data Center (NCDC), the normal high is 80 and the normal low is 59. I've calculated the 32-year averages at 82 and 60.

On the hot side, in 1988 the high was the record high of 104 with a low of 73, a 31 degree spread. In 1953 the high was also 104. The high of 104 in 1988 tied July 13, 1995 as the hottest temperature ever in O'Hare's history. In 1995 the high was 95 with a low of 74. 1988 and 1995 were two of our hottest summers. Two years later, in 1997, the high was 89 with a low of 74. Five years later, in 2002, the high was 91 with a low of 72, our most recent 90s high and most recent 70s low. Another hot high was 94 in 1991. The other 90s highs were 91 in 1998, 90 in 1994 and 90 in 1979. The record warmest low of 78 occurred in 1953. 24 of the past 32 highs (75%) were in the: 70s (13) and 80s (11). Seven highs (22%) were in the hot: 90s (6) and 100s (1). One high was in the cool 50s. There have been no highs in the 60s the last 32 years!

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 90 with a low of 60, a 30 degree spread. In 1970 the high was a cool 65 degrees. In 1969 the high was a cool 62 with a low of 49, a cool day. In 1963 the high was 63 with a low of 46, a cool day. In 1961 the high was 65 with a low of 47, a cool day. In 1960 the high was a cool 68 degrees.

More recently, the spreads were large: 34 degrees in 2005 (86/52), 33 degrees in 1980 (76/43), 33 degrees in 1985 (77/44) and 32 degrees in 1991 (94/62).

On the cool side, in 1992 the high was the record coolest high of 57 with the co-record low of 43. In 2003 the high was 73 with a low of 45. Other cool lows were the co-record low of 43 in 1980 and 44 in 1985. 16 of the last 32 lows (50%) were in the 60s. Twelve lows (38%) were in the cool: 40s (5) and 50s (7). Four lows (12%) were in the warm 70s.

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 20:33 and twilight ends at 21:08. There's a total of 15 hours, 16 minutes of daylight today and 16 hours, 26 minutes between twilights. We gained no minutes of daylight from yesterday. Tomorrow twilight begins at 4:42 and sunrise is at 5:17. The moon is waning gibbous. Illumination was 80% at midnight, will be 75% at noon and 71% at midnight tonight. Moonset is at 10:21 this morning. Moonrise is at 23:34 tonight. Moonset is at 11:22 tomorrow morning. Moonlight time is 10 hours, 47 minutes which is 38 minutes longer than yesterday.

Summer began June 4 and runs for 110 days through September 21. High temperatures in this period are usually in the 70s and 80s. Highs in the 60s, 90s and 100s occur infrequently. Independence Day is in 14 days.