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 32-year averages at 71 and 50.

On the warm side, last year, in 2010, the high was 89 with a low of 62. In 2007 the high was 89 with a low of 60. In 1991 the high was 82 with a low of 66. The record high of 92 was set in 1977. It was also 92 in 1921 and 1964. The record warmest low of 71 occurred in 1964. 28 of the last 32 lows (88%) highs were in the: 60s (10), 70s (10) and 80s (8). Our most recent 60s high was 64 in 2003. Four highs were in the cool 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 degrees. In 1975 the high was a warm 85 with a low of 60, a warm day. In 1973 the high was a cool 59 degrees. In 1972 the high was a warm 84 degrees. 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 degrees. 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 degrees. In 1961 the high was 67 with a cold low of 35, a 32 degree spread. In 1959 the high was a cool 56 degrees.

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 two years ago in 2009 (80/50).

On the cool side, in 1987 the high was 55 with a low of 47. Three years ago, in 2008, 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 last 31 lows (84%) were in the: 40s (16) and 50s (11). One low was in the cold 30s. Four lows were in the warmer 60s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:52 and sunrise is at 5:25. Sunset is at 20:15 and twilight ends at 20:48. There's a total of 14 hours, 50 minutes of daylight today and 15 hours, 56 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 4:52 and sunrise is at 5:25. The moon is waning gibbous and reaches last quarter tomorrow at 13:52. Illumination was 65% at midnight, will be 60% at noon and 55% at midnight tonight. Moonrise is at 0:41 this morning. Moonset is at 11:33 this morning. Moonrise is at 1:07 tomorrow morning. Moonlight time is 10 hours, 52 minutes which is 33 minutes longer 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. Memorial Day is in seven days. -Bernie-