May 21: ORD

Today is May 21st. It's the 141st day of the year. 224 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 71 and the normal low is 50. I've calculated the 31-year averages at 72 and 47.

On the warm side, in 1987 the high was 89 with a low of 59, a 30 degree spread. Other highs of note are 87 in 1994, 86 in 1992 and 84 in 1991. The record high of 92 was set in 1977. The record warmest low of 71 was set in 1921. 11 of the last 30 highs have been 70s. Eight highs were in the warmer 80s. 12 highs were in the cooler: 50s (5) and 60s (7).

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: In 1978 the high was a cool 57 with a low of 41, a cool day. In 1977 the high was 91 with a low of 67, a hot day. In 1975 the high was 79 with a warm low of 66, a warm day. In 1974 the high was 84 with a low of 66, a warm day. In 1972 the high was a warm 84. In 1970 the high was 86 with a low of 66, a warm day. In 1969 the high was a cool 57 with a low of 42, a cool day. In 1965 the high was a warm 83 with a low of 50, a 33 degree spread. In 1964 the high was 81 with a low of 39, a 42 degree spread. In 1963 the high was a cool 58. In 1961 the high was 58 with a low of 36, a cool day. In 1959 the high was 86 with a low of 64, a warm day.

More recently, we had large spreads of 37 degrees in 1980 (82/45), 36 degrees in 1994 (87/51), 36 degrees three years ago (80/44), 32 degrees in 1981 (79/47), 30 degrees in 1989 (80/50), 30 degrees in 1991 (84/54), 30 degrees in 1992 (86/56) and 30 degrees in 2005 (73/43).

On the cool side, in 2002 the high was 58 with the record low of 31 (former record lows were 36 in both 1883 and 1997). In 1997 the high was 58 with a low of 36. In 1979 the high was 58 with a low of 38. Other highs of note were 57 in 2003 and 58 in 1990. The record coolest high of 42 occurred way back in 1883. 27 of 31 (87%) lows were: 40s (15) and 50s (12). Three lows were in the colder 30s. One low was in the warmer 60s (60 last year).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:54 and sunrise was at 5:27. Sunset is at 20:14 and twilight ends at 20:47. There's a total of 14 hours, 47 minutes of daylight today and 15 hours, 53 minutes between twilights. Tomorrow twilight begins at 4:53 and sunrise is at 5:26. The moon reached first quarter yesterday at 18:43 and is waxing gibbous. Illumination was 53% at midnight, will be 59% at noon and 64% at midnight tonight. Moonset was at 1:38 this morning. Moonrise is at 13:27 this afternoon. Moonset is 2:04 tomorrow morning. Moonrise is at 14:40 tomorrow. Moonlight time is 12 hours, 11 minutes which is 45 minutes shorter than yesterday.

National Maritime Day is tomorrow and Memorial Day is in ten days. - Bernie -