June 18: ORD

Today is June 18th. It's the 169th day of the year. 196 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 59.

On the hot side, in 1995 the high was 93 with the only 70s low of 71. A year earlier, in 1994, the high was 94 with a low of 68. Other hot highs were 95 in 1987 and 92 in 1988. The other 90s highs were 91 in 2001 and 90 last year in 2010. The record high of 98 was set in 1954. The record warmest low of 77 occurred in 1921. 23 of the past 32 highs (72%) were in the: 70s (9) and 80s (14). Seven highs (22%) were in the 90s, including 90 last year (in 2010). Two highs 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 81 with a low of 51, a 30 degree spread. In 1965 the high was 75 with a cool low of 44, a 31 degree spread. In 1963 the high was 85 with a low of 53, a 32 degree spread. In 1961 the high was 81 with a low of 51, a 30 degree spread.

More recently, five spreads were large: 36 degrees in 1988 (92/56), 33 degrees in 2003 (90/57), 32 degrees in 1993 (85/53), 30 degrees in 1986 (81/51) and 30 degrees in 1987 (95/65).

On the cool side, in 1982 the high was 64 with a low of 52. In 1999 the high was 73 with the record low of 45. Another cool high was 66 in 1979. The record coolest high of 55 occurred in 1950. 30 of the last 32 lows (94%) were in the: 50s (16) and 60s (14). One low was in the cool 40s (the record low) and one was in the warm 70s (71 in 1995).

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 20:32 and twilight ends at 21:07. There's a total of 15 hours, 15 minutes of daylight today and 16 hours, 25 minutes between twilights. We lost a minute of daylight from yesterday. Tomorrow twilight begins at 4:42 and sunrise is at 5:17. The moon is waning gibbous and was full three days ago as the full Strawberry moon at 15:14. Other names for this moon are Rose and Hot. Illumination was 93% at midnight, will be 90% at noon and 87% at midnight tonight. Moonset is at 8:12 this morning. Moonrise is at 22:40 tonight. Moonset is at 9:17 tomorrow morning. Moonlight time is 9 hours, 32 minutes which is 34 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. Father's Day is tomorrow. Independence Day is in 16 days.