June 12: ORD

Today is June 12th. It's the 163rd day of the year. 202 days remain. It's week 24 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 79 and the normal low is 56. I've calculated the 32-year averages at 79 and 58.

On the hot side, three years ago, in 2008, the high was 91 with a low of 73. In 1987 the high was 93 with a low of 67. All of the 90s highs (except three years ago) occurred between 1983 and 1988. The other 90s highs were 93 in 1983, 91 in 1984 and 90 in 1988. Our other upper 60s lows were 68 in 1990 and 67 in 1999. Our other 70s low was 70 in 2005. The record high of 97 was set in 1956. The record warmest low of 75 occurred back in 1920. 22 of the past 32 highs (69%) were in the: 70s (10) and 80s (12). Five highs (16%) were in the hot 90s. Five highs (15%) were in the cool: 50s (1) and 60s (4).

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1978 the high was 78 with a low of 48, a 30 degree spread. In 1977 the high was a cool 63 with a low of 57, a six degree spread. In 1976 the high was a hot 94 with a low of 66, a hot day. In 1970 the low was a warm 68 degrees. In 1967 the high was 90 with a warm low of 72, a hot day. In 1965 the high was 80 with a low of 50, a 30 degree spread. In 1961 the high was 89 with a warm low of 68, a warm day. In 1960 the high was a cool 59 with a low of 55, a four degree spread.

More recently, the spreads were all large: 36 degrees in 1988 (90/54), 35 degrees in 1984 (91/56), 35 degrees in 1992 (86/51) and 33 degrees in 1983 (93/60).

On the cool side, in 1985 the only 50s high of 57 occurred with the record low of 40. In 2000 the high was 60 with a low of 53, a seven degree spread. Another cool high of 67 degrees occurred in 2003. The record coolest high of 55 occurred in 1955. 27 of the last 32 lows (84%) were in the: 50s (13) and 60s (14). Three lows were in the cool 40s (most recently 49 two years ago in 2009) and two were in the warm 70s (most recently 73 three years ago in 2008).

Yesterday's high of 62 and low of 52 (mean of 57) was the second coolest June 11th of at least the last 33 years. It was just half a degree cooler than 1980 (a nice high of 74 with a cold low of 41, a mean of 57.5). 1985 remains the coolest June 11 as the high that day was a very cool 56 with a low of 48 for a mean of 52.

The 45 degree drop in temperature from last Wednesday's high of 95 (6/8/11) to the low of 50 late Thursday (6/9/11) was the greatest two-day drop in temperature since the June record drop of 49 degrees in 1988, 23 years ago. The drop in 1988 was from a high of 103 on June 25 to a low of 54 on June 26. The all-time record, irregardless of month, was a 61 degree drop from 74 degrees to 13 degrees on November 11 and 12, 1911. Data courtesy of The Chicago Weather Center Blog.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:42 and sunrise is at 5:16. Sunset is at 20:30 and twilight ends at 21:05. There's a total of 15 hours, 14 minutes of daylight today and 16 hours, 23 minutes between twilights. We gained one minute of daylight from yesterday. Tomorrow twilight begins at 4:42 and sunrise is at 5:16. The moon is waxing gibbous. Illumination was 84% at midnight, will be 88% at noon and 91% at midnight tonight. Moonset is at 2:30 this morning. Moonrise is at 17:22 this afternoon. Moonset is at 3:11 tomorrow morning. Moonlight time is 9 hours, 8 minutes which is 39 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. Flag Day is in two days. Father's Day is in seven days.