May 18: ORD

Today is May 18th. It's the 138th day of the year. 227 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 70 and the normal low is 49. I've calculated the 31-year averages at 69 and 49.

On the warm side, in 1996 the high was 90 with the record-tying warmest low of 72 (tied with 1911). In 1984 the high was 91 with a low of 61, a 30 degree spread. In 1998 the high was 90 with a low of 62. In 1979 the high was 85 with a low of 60. In 1982 the high was 82 with a low of 61. The record high of 93 was set in 1962. 25 highs over the last 31 years have been: 50s (7), 60s (9) and 70s (9). Six highs were in the warmer: 80s (3) and 90s (3).

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 92 with a low of 64, a hot day. In 1975 the high was a hot 86 with a low of 50, a 36 degree spread and hot day. In 1974 the high was a cool 58. In 1972 the high was a warm 85. In 1971 the high was 85 with a low of 69, a warm day. In 1970 the high was 78 with a low of 45, a 33 degree spread. In 1969 the high was a cold 47 with a low of 45, a two degree spread and cold day. In 1967 the high was a warm 85 with a low of 55, a 30 degree spread. In 1965 the high was a warm 82 with a low of 46, a 36 degree spread. In 1964 the high was a hot 89 with a low of 56, a 33 degree spread and hot day. In 1962 the high was 91 with a low of 71, a hot day and year of the record high. In 1961 the high was a cool 55 with a low of 41, a cool day.

More recently, we had large spreads of 36 degrees in 1997 (77/41), 33 degrees in 1993 (70/37), 30 degrees in 1987 (81/51) and 30 degrees in 1988 (70/40).

On the cool side, in 2002 the high was 54 with the record low of 34 degrees (broke the former record of 35 set way back in 1894). Other cool highs were 54 in 1991, 55 in 1986, 55 two years ago, 57 in 1981 and 58 in 1995. Another cold low was 37 in 1993. The record coolest high of 45 was set way back in 1900. 17 of the last 31 lows (55%) were 40s. Three lows were in the colder 30s. 11 lows were in the warmer: 50s (6), 60s (4) and 70s (1).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:57 and sunrise was at 5:29. Sunset is at 20:11 and twilight ends at 20:43. There's a total of 14 hours, 42 minutes of daylight today and 15 hours, 46 minutes between twilights. Tomorrow twilight begins at 4:56 and sunrise is at 5:28. The moon is waxing crescent. Illumination was 21% at midnight, will be 25% at noon and 31% at midnight tonight. Moonset was at a minute past midnight. Moonrise was at 9:46 this morning. Moonset is 38 minutes past midnight tonight. Moonrise is at 11:00 tomorrow morning. Moonlight time is 14 hours, 15 minutes which is an hour and 12 minutes shorter than yesterday.

National Maritime Day is in four days. - Bernie -