June 5: ORD

Today is June 5th. It's the 156th day of the year. 209 days remain. It's week 23 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 76 and the normal low is 54. I've calculated the 32-year averages at 75 and 51.

On the hot side, in 2005 the high was 87 with a low of 68. In 1984 the high was 88 with a low of 66. Other hot highs include 89 in both 1988 and 1999. The record high of 97 occurred in 1971 and the record warmest low of 77 occurred back in 1925. 24 of the past 32 highs (75%) were in the: 70s (13) and 80s (11). Eight highs (25%) were in the cool: 50s (2) and 60s (6).

Yesterday, June 4, was the warmest June 4 O'Hare has ever seen. The high was 92 with a low of 64. It was also only the third June 4 high in the 90s. The other 90s were 96 in 1977 (year of the record high) and 90 in 1971.

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1977 the high was 87 with a warm low of 66, a hot day. In 1974 the high was 73 with a warm low of 66, a small seven degree spread. In 1971 the high was 92 with a low of 68, a hot day and year of the record high. The same high and low in 1971 happened on both the 5th and 6th, a very rare occurrence. In 1966 the high was 86 with a warm low of 68, a hot day. In 1963 the high was 87 with a warm low of 66, a hot day. In 1961 the high was 86 with a low of 50, a 36 degree spread.

More recently, there were large spreads of 35 degrees in 1994 (87/52), 35 degrees two years ago (in 2009) (79/44), 34 degrees in 1987 (87/53), 33 degrees in 2004 (77/44), 33 degrees in 2006 (81/48), 32 degrees in 1988 (89/57), 31 degrees in 1981 (86/55) and 31 degrees in 2003 (78/47).

On the cool side, in 1998 the high was 58 with a low of 42. In 2001 the high was 58 with a low of 47. In 1990 the high was 63 with a low of 42. Other cool highs were 61 in 1986, 63 in 2000 and 64 in 2007. The record low of 37 was set in 1945 and the record coolest high of 45 occurred way back in 1894. 27 of the last 32 lows (84%) were in the: 40s (15) and 50s (12). Five lows (16%) were in the warm 60s. All 12 lows in the 50s (over the past 32 years) happened between 1979 and 1995, most recently 55 in 1995. All lows from 1996 onward have been in the 40s or 60s. 4 of the 5 lows in the 60s happened from 1999 to 2010. The lone exception was a low of 66 in 1984, the warmest day until 2005.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:44 and sunrise is at 5:18. Sunset is at 20:26 and twilight ends at 21:00. There's a total of 15 hours, 8 minutes of daylight today and 16 hours, 16 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 4:44 and sunrise is at 5:18. The moon is waxing crescent. Illumination was 12% at midnight, will be 16% at noon and 20% at midnight tonight. Moonrise is at 8:58 this morning. Moonset is at 23:27 tonight. Moonrise is at 10:07 tomorrow morning. Moonlight time is 14 hours, 29 minutes which is 33 minutes shorter than yesterday.

Summer began yesterday 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. Flag Day is in nine days.