May 24: ORD

Today is May 24th. It's the 144th day of the year. 221 days remain. It's week 21 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 73 and the normal low is 50. I've calculated the 31-year averages at 70 and 50.

On the warm side, in 1991 the high was 85 with the record warmest low of 68. The former record warmest low of 67 occurred in 1933. Two years earlier, in 1989, the high was 86 with a low of 65. Three years ago the high was 88 with a low of 63. To round out the highs in the 80s, it was 84 in 1997, 80 in 2000 and 80 three years ago. The record high of 93 was last tied in 1950, as it was also 93 in 1921. 20 of the 31 (65%) highs were: 60s (10) and 70s (10). Six highs were in the warmer 80s and five highs were in the cooler: 40s (1) and 50s (4).

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: In 1977 the high was 91 with a low of 64, a hot day. In 1976 the high was a cool 60. In 1975 the high was 85 with a low of 62, a warm day. In 1972 the high was a hot 86 with a low of 54, a 32 degree spread. In 1965 the high was 83 with a low of 53, a 30 degree spread. In 1961 the high was 80 with a low of 45, a 35 degree spread. In 1960 the high was a cool 60.

More recently, there was a small spread of six degrees in 1999 (54/48). There were large spreads of 34 degrees in 1985 (78/44), 32 degrees in 1983 (76/44), 31 degrees in 1997 (84/53) and 31 degrees in 2006 (80/49).

On the cool side, there was one day of a mean of 11.5 or more degrees below normal. That was in 1992 when the high was 46 with the record low of 34. Other cool highs of note were 61 in 1982, 60 in 2001, 57 in 1995, 56 in 1987, 56 in 1996 and 54 in 1999. The record coolest high of 44 occurred back in 1925. 17 of the 31 lows were 40s. One low was in the colder 30s. 13 lows were in the warmer: 50s (10) and 60s (3).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:51 and sunrise was at 5:24. Sunset is at 20:16 and twilight ends at 20:50. There's a total of 14 hours, 52 minutes of daylight today and 15 hours, 59 minutes between twilights. Tomorrow twilight begins at 4:51 and sunrise is at 5:24. The moon is waxing gibbous. Illumination was 84% at midnight, will be 88% at noon and 91% at midnight tonight. Moonset was at 2:58 this morning. Moonrise is at 17:05 this afternoon. Moonset is 3:28 tomorrow morning. Moonlight time is 9 hours, 53 minutes which is 45 minutes shorter than yesterday.

Memorial Day is in a week. - Bernie -