May 23: ORD

Today is May 23rd. It's the 143rd day of the year. 222 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 72 and the normal low is 50. I've calculated the 31-year averages at 71 and 50.

On the warm side, three years ago the high was 89 with a low of 60. In 1991 the high was 82 with a low of 66. In 1989 the high was also 82. To round out the highs in the 80s, it was 81 in 2000, 81 in 2004, 80 in 1994 and 80 last year. The only other 60s low was 61 in 1981. The record high of 92 was set in 1977. It was also 92 degrees in 1921 and 1964. The record warmest low of 71 was set in 1964. 20 of the 31 (65%) highs were: 60s (10) and 70s (10). Seven highs were in the warmer 80s and four highs were in the cooler 50s.

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 66, a hot day and year of the record high. In 1976 the high was a cool 59. In 1975 the high was a warm 85 with a low of 60, a warm day. In 1973 the high was a cool 59. In 1972 the high was a warm 84. In 1968 the high was a cool 55 with a low of 52, a three degree spread. In 1967 the high was 72 with a low of 40, a 32 degree spread. In 1966 the high was a warm 85. In 1964 the high was 88 with a low of 70, a hot day and year of the record warmest low. In 1963 the high was 60 with a low of 32, a cool day. In 1962 the low was a warm 64. In 1961 the high was 67 with a cool low of 35, a 32 degree spread. In 1959 the high was a cool 56.

More recently, there were large spreads of 37 degrees in 2006 (75/38), 33 degrees in 1985 (73/40), 32 degrees in 1997 (73/41) and 30 degrees last year (80/50).

On the cool side, there were no days of a mean of 11.5 or more degrees below normal. However, the two coolest days were within half a degree of each other. In 1987 the high was 55 with a low of 47. Two years ago the high was 57 with a low of 46. Other cool highs of note were 57 in 1982 and 58 in 1988. The only low in the 30s was 38 in 2006. That low of 38 was just a degree warmer than the record low of 37, set back in 1917. The record coolest high of 50 occurred back in 1931. 27 of the 31 (87%) lows were: 40s (16) and 50s (11). One low was in the colder 30s. Three lows were in the warmer 60s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:52 and sunrise was at 5:25. Sunset is at 20:16 and twilight ends at 20:49. There's a total of 14 hours, 51 minutes of daylight today and 15 hours, 57 minutes between twilights. Tomorrow twilight begins at 4:51 and sunrise is at 5:24. The moon is waxing gibbous. Illumination was 75% at midnight, will be 80% at noon and 84% at midnight tonight. Moonset was at 2:30 this morning. Moonrise is at 15:52 this afternoon. Moonset is 2:58 tomorrow morning. Moonrise is at 17:05 tomorrow. Moonlight time is 10 hours, 38 minutes which is 46 minutes shorter than yesterday.

Memorial Day is in eight days. - Bernie -