June 30: ORD

Today is June 30th. It's the 181st day of the year. 184 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.

According to the National Climatic Data Center (NCDC), the normal high is 82 and the normal low is 61. I've calculated the 32-year averages at 80 and 59.

On the hot side, in 1996 the high was 94 with a low of 73. In 2005 the high was 91 with a low of 72. Our most recent 90s high and 70s low occurred in 2005. The other 90s highs were 93 in 2002 and 91 in 1990. The record high of 99 was tied in 1953, after first being set in 1913. The record warmest low of 80 occurred back in 1931. 25 of the past 32 highs (78%) were in the: 70s (10) and 80s (15). Four highs were in the hot 90s and two 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 1970 the high was 93 with a warm low of 78, a hot day. In 1968 the low was a warm 73 degrees. In 1966 the high was 90 with a low of 60, a 30 degree spread. In 1965 the high was 68 with a low of 44, a cool day. In 1963 the high was 92 with a low of 62, a 30 degree spread.

More recently, there was a small spread of seven degrees two years ago, in 2009 (66/59). The large spreads were: 34 degrees in 1989 (83/49), 32 degrees in 2006 (85/53) and 30 degrees in 1979 (81/51).

On the cool side, in 1982 the high was 70 with a low of 47. Four years later, in 1986, the high was 64 with a low of 59, a small five degree spread. The other 40s low was 49 in 1989. The other cool highs were 66 two years ago in 2009 and 69 in 1993. The record low of 45 was set in 1943. The record coolest high of 59 occurred way back in 1902. 28 of the last 32 lows (88%) were in the: 50s (18) and 60s (10). Two lows were in the cold 40s and two were in the warm 70s. Although there have been ten 60s lows, our most recent one was 62 in 2004. Lows over the last five years were in the 50s. Just before that, in 2005, the low was 72. The forecast low for today by the National Weather Service/Chicago is "around 60."

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:46 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, 22 minutes between twilights. We lost no minutes of daylight from yesterday. Tomorrow twilight begins at 4:46 and sunrise is at 5:21. The moon is waning crescent and will reach new tomorrow morning at 3:54. Illumination was 1% at midnight, will be 0% at noon and 0% at midnight tonight. Moonrise is at 4:35 this morning. Moonset is at 20:06 tonight. Moonrise is at 5:37 tomorrow morning. Moonlight time is 15 hours, 31 minutes which is 6 minutes shorter 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 four days.