June 13: ORD

Today is June 13th. It's the 164th day of the year. 201 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 57. I've calculated the 32-year averages at 81 and 59.

On the hot side, in 1990 the high was 92 with our only 70s low of 71. In 2001 the high was 91 (our most recent 90s high) with a low of 68. In 1988 we had a near-record high of 94 (record is 95, first set in 1954 and tied a couple years later in 1956). The high was 92 in 1987. Highs were 91 in both 1992 and 1994. As you can see, five of the six 90s highs occurred between 1987 and 1994. Another warm low was 69 in 1984. The record warmest low of 74 occurred back in 1920. 24 of the past 32 highs (75%) were in the: 70s (11) and 80s (13). Six highs were in the hot 90s and two were in the cool 60s, most recently 68 two years ago in 2009.

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 67 with a low of 42, a cool day. In 1969 the high was a cool 64 degrees. In 1968 the high was 76 with a cool low of 43, a 33 degree spread. In 1965 the high was a cool 65 with a low of 46, a cool day. In 1964 the high was a hot 91 degrees. In 1963 the high was 80 with a low of 49, a 31 degree spread. In 1962 the low was a cold 44 degrees. In 1960 the high was a cool 63 with a low of 56, a seven degree spread. In 1959 the high was a cool 67 degrees.

More recently, all the spreads were all large: 36 degrees in 1992 (91/55), 34 degrees in 1995 (85/51), 31 degrees in 1982 (78/47), 31 degrees in 1988 (94/63) and 30 degrees in 1987 (92/62).

On the cool side, in 1985 the high was 71 with the record low of 40, a 31 degree spread. In 2002 the high was 64 (just two degrees above the record coolest high of 62 set way back in 1875). 28 of the last 32 lows (88%) were in the: 50s (11) and 60s (17). Three lows were in the cool 40s and one was in the warm 70s.

Yesterday's high of 64 and low of 50 (mean of 57) was the third coolest June 12th of at least the last 33 years. The coolest June 12 remains 1985 (high of 57, low of 40). The second coolest (by just half a degree over this year) remains 2000 (high of 60, low of 53).

Saturday'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 20:31 and twilight ends at 21:05. There's a total of 15 hours, 15 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 and will be full in two days as the full Strawberry moon at 15:14. Other names for this moon are Rose and Hot. Illumination was 91% at midnight, will be 94% at noon and 97% at midnight tonight. Moonset is at 3:11 this morning. Moonrise is at 18:34 this afternoon. Moonset is at 4:00 tomorrow morning. Moonlight time is 8 hours, 37 minutes which is 31 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 tomorrow. Father's Day is in six days.