May 12: ORD

Today is May 12th. It's the 132nd day of the year. 233 days remain. It's week 19 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 68 and the normal low is 46. I've calculated the 32-year averages at 67 and 46.

On the warm side, in 2004 the high was 85 degrees with the record warmest low of 66. The record warmest low of 66 originally occurred in 1956. In 1991 the high was 84 with a low of 63. In 2000 the high was 85 with a low of 60. In 1992 the high was 77 with a low of 62. Other 80s highs were 84 in 1993, 81 in 1982, 80 in 1985 and 80 in 1988. The only other upper 70s high was 79 in 1998. The record high of 92 was set in 1956. 31 of the last 32 highs (97%) were in the: 50s (9), 60s (8), 70s (7) and 80s (7). On the cold side, one high was in the 40s (47 in 2006).

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: In 1974 the high was a cool 55 with a low of 48, a seven degree spread. In 1973 the high was a cool 56 degrees. In 1970 the high was a warm 81 with a low of 49, a 32 degree spread. In 1968 the high was 77 with a low of 46, a 31 degree spread. In 1967 the high was a cool 52 with a low of 38, a cool day. In 1966 the high was a cold 44 with a low of 40, a four degree spread and cold day. In 1965 the high was a warm 81 with a low of 47, a 34 degree spread. In 1961 the high was a warm 83 with a low of 50, a 33 degree spread. In 1960 the low was a cold 34 degrees.

More recently, we had large spreads of 43 degrees in 1993 (84/41), 32 degrees in 1998 (79/47), 32 degrees in 2009 (71/39), 31 degrees in 1981 (62/31) and 30 degrees in 1982 (81/51). The small spreads were seven degrees last year (in 2010) (51/44) and five degrees in 2002 (50/45).

On the cool side, in 2006 the high was 47 with a low of 36. A decade earlier, in 1996, the high was 50 with a low of 35. The other 30s lows were the record low of 31 in 1981, 38 in 1989, 38 in 2001 and 39 two years ago in 2009. The other cool highs (lower and mid 50s) were: 50 in 2002, 51 last year (in 2010), 54 in 1979, 55 in 1990, 55 in 2005 and 56 three years ago in 2008. The record coldest high of 43 occurred back in 1912. Another cold high of 44 occurred way back in 1882. 17 of the last 32 lows (53%) were in the 40s. Six lows (19%) were in the cold 30s. Nine lows (28%) were in the warmer: 50s (5) and 60s (4).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight is at 5:04 and sunrise is at 5:36. Sunset is at 20:04 and twilight ends at 20:36. There's a total of 14 hours, 28 minutes of daylight today and 15 hours, 32 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:03 and sunrise is at 5:35. The moon is waxing gibbous, having reached first quarter two days ago at 15:33. Illumination was 66% at midnight, will be 71% at noon and 76% at midnight tonight. Moonset is at 2:24 this morning. Moonrise is at 14:39 this afternoon. Moonset is at 2:53 tomorrow morning. Moonlight time is 11 hours, 45 minutes which is 43 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) began on April 13. Warm Spring runs for 52 days, through June 3. High temperatures in this period are usually in the 50s, 60s and 70s. Warmer 80s and 90s occur infrequently. Armed Forces Day is in nine days. -Bernie-