June 21: ORD

Today is June 21st. It's the 172nd day of the year. 193 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 81 and the normal low is 59. I've calculated the 32-year averages at 83 and 61.

On the hot side, in 1988 the high was the record high of 101 with a low of 71, a 30 degree spread. In 2002 the high was 88 with a low of 71. The other 90s highs were 93 in 1991, 92 in 1986 and 91 in 1983. The other 70s low was 70 in 2009. The record warmest low of 74 occurred back in 1923. 20 of the past 32 highs (63%) were in the 80s. Four highs (12%) were in the hot: 90s (3) and 100s (1). Eight highs (25%) were in the cool: 60s (3) and 70s (5).

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1972 the high was a cool 68 degrees. In 1969 the high was 65 with a low of 46, a cool day. In 1968 the high was a hot 93 degrees. In 1967 the high was a cool 68 degrees. In 1963 the high was 64 with a low of 41, a cool day. In 1962 the high was 83 with a low of 53, a 30 degree spread. In 1961 the high was 75 with a cold low of 44, a 31 degree spread.

More recently, the spreads were large: 33 degrees in 2003 (80/47), 30 degrees in 1986 (92/62) and 30 degrees in 1991 (93/63).

On the cool side, in 1992 the high was 61 with the record low of 38. In 2001 the high was 69 with a low of 55. Another cool low was 47 in 2003. Another cool high was 67 in 2004. The record coolest high of 56 occurred way back in 1881. 19 of the last 32 lows (59%) were in the 60s. Ten lows (31%) were in the cool: 30s (1), 40s (1) and 50s (8). Three lows (10%) 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 4:43 and sunrise is at 5:17. The moon is waning gibbous. Illumination was 71% at midnight, will be 67% at noon and 62% at midnight tonight. Moonset is at 11:22 this morning. Moonrise is at 23:57 tonight. Moonset is at 12:22 tomorrow afternoon. Moonlight time is 11 hours, 25 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 13 days.