May 30: ORD

Today is May 30th. It's the 150th day of the year. 215 days remain. It's week 22 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 75 and the normal low is 52. I've calculated the 31-year averages at 77 and 55.

On the hot side, in 2006 the high was 89 degrees with a low of 67. In 1991 the high was 88 with a low of 66. Three years later, in 1994, the high was 90 with a low of 64. In 1987 the high was 85 with a low of 68. Two decades later (three years ago) the high was 87 with a low of 66. In 1980 the high was 86 with a low of 66. In 1988 the high was 91 with a low of 60, a 31 degree spread. The other 80s high of note was 87 in 1998. The other warm lows were 64 in both 1985 and 2002. The record high of 93 was set in 1942 and tied in 1953. The record warmest low of 72 was set back in 1921. 13 of the past 31 highs were 80s. 16 highs were in the cooler: 50s (1), 60s (7) and 70s (8). Two highs were in the warmer 90s.

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: In 1971 the high was 82 with a low of 45, a 37 degree spread. In 1970 the low was a warm 68. In 1967 the high was a cool 63. In 1964 the high was 69 with a cold low of 34, a 35 degree spread and cool day. In 1963 the high was 74 with a low of 41, a 33 degree spread. In 1962 the low was a warm 67. In 1961 the high was 76 with a cold low of 37, a 39 degree spread.

More recently, there were large spreads of 31 degrees in 1984 (70/39) and 31 degrees in 2000 (80/49).

On the cool side, in 1983 the high was the only 50s high of the past 31 years at 55 degrees with a low of 45. In 1996 the high was 65 with a low of 36. Five years later, in 2001, the high was 60 with a low of 45. Another cool low was 39 in 1984. Both records were set way back in the 19th century. The record low of 35 was set in 1873. The record coolest high of 42 was set in 1889. 29 of the last 31 lows were: 40s (9), 50s (9) and 60s (11). Two lows were in the colder 30s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:47 and sunrise was at 5:21. Sunset is at 20:22 and twilight ends at 20:55. There's a total of 15 hours, 1 minute of daylight today and 16 hours, 8 minutes between twilights. Tomorrow twilight begins at 4:46 and sunrise is at 5:20. The moon is waning gibbous. Illumination was 95% at midnight, will be 92% at noon and 89% at midnight tonight. Moonset was at 7:29 this morning. Moonrise is at 23:00 tonight. Moonset is 8:31 tomorrow morning. Moonlight time is 8 hours, 29 minutes which is 19 minutes longer than yesterday.

Memorial Day is tomorrow. - Bernie -