May 15: ORD

Today is May 15th. It's the 135th day of the year. 230 days remain. It's week 20 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 69 and the normal low is 47. I've calculated the 31-year averages at 69 and 48.

On the warm side, in 1998 the high was 86 with a low of 64. In 1991 the high was 87 with a low of 57, a 30 degree spread. In 1988 the high was 80 with a low of 63. In 2001 the high was 88 with a low of 55, a 33 degree spread. In 1982 the high was 85 with a low of 56. Three years ago the high was 80 with a low of 57. The record high of 91 and record warmest low of 71 were set on the same day in 1962. There's a fairly even distribution of highs over the last 31 years: 50s (7), 60s (10), 70s (8) and 80s (6).

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 a warm 82. In 1971 the high was a warm 83 with a low of 58, a warm day. In 1968 the high was 82 with a low of 60, a warm day. In 1967 the high was a cool 56. In 1965 the high was 81 with a low of 60, a warm day. In 1964 the high was a warm 81 with a low of 45, a 36 degree spread. In 1963 the high was a cool 55. In 1962 the high was 89 with a low of 71, a hot day. 1962 was also the year of the record high and record warmest low. In 1960 the high was a warm 82. In 1959 the high was a cool 55.

More recently, we had large spreads of 35 degrees in 1992 (77/42) and 35 degrees in 2002 (75/40).

On the cool side, in 1997 the high was 51 with a low of 38. In 1983 the high was 53 with a low of 37. The other highs in the mid 50s were 54 in 2005, 55 in 2004, 57 in 2003 and 57 two years ago. The other 30s lows were 38 in 1984 and 39 in 2004. The record low of 35 was set way back in 1895. The record coolest high of 44 was set back in 1904. 17 of the last 31 lows were 40s. Four lows were in the colder 30s. Ten lows were in the warmer: 50s (8) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:00 and sunrise was at 5:32. Sunset is at 20:08 and twilight ends at 20:40. There's a total of 14 hours, 36 minutes of daylight today and 15 hours, 40 minutes between twilights. Tomorrow twilight begins at 4:59 and sunrise is at 5:31. The moon is waxing crescent and reached new two days ago at 20:04. Illumination was 2% at midnight, will be 4% at noon and 6% at midnight tonight. Moonrise was at 6:25 this morning. Moonset is at 22:21. Moonrise is at 7:25 tomorrow morning. Moonlight time is 15 hours, 56 minutes which is 12 minutes longer than yesterday. Too bad there's so little of it to see!

Armed Forces Day is today. A sister of mine, Maria, celebrates a birthday tomorrow. - Bernie -