May 17: ORD

Today is May 17th. It's the 137th day of the year. 228 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 48. I've calculated the 31-year averages at 71 and 48.

On the warm side, in 2001 the high was 85 with a low of 62. In 1982 the high was 87 with a low of 56, a 31 degree spread. Other 80s highs of note were 89 in 1987, 88 in 1996, 86 in 1998, 85 in 1984 and 82 in 1992. Another warm low was 62 in 1999. The record high of 94 was set in 1962 and the record warmest low of 70 was set in 1977. 26 of the highs over the last 31 years have been: 60s (10), 70s (6) and 80s (10). Five highs were in the cooler: 40s (1) and 50s (4).

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 86 with a low of 63, a hot day and year of the record warmest low. In 1975 the high was 74 with a low of 43, a 31 degree spread. In 1972 the high was 80 with a low of 50, a 30 degree spread. In 1971 the high was a hot 88 with a low of 48, a 40 degree spread and hot day. In 1967 the high was 74 with a low of 44, a 30 degree spread. In 1964 the high was 80 with a low of 49, a 31 degree spread. In 1962 the high was 92 with a low of 71, a hot day. 1962 was also the year of the record high.

More recently, we had a small spread of seven degrees in 1980 (56/49). The large spreads were: 40 degrees in 1984 (85/45), 39 degrees in 1996 (88/49), 38 degrees in 1987 (89/51), 36 degrees in 1998 (86/50), 35 degrees in 1989 (80/45) and 30 degrees in 1992 (82/52).

On the cool side, in 2002 the record coolest high of 45 was established (broke the former record of 46 degrees in 1945). The low in 2002 was 36. This ties the record which was set in 1973. In 1983 the high was 58 with a low of 37. Other cool highs were 55 in 1981, 56 in 1980 and 59 in 1994. 15 of the last 31 lows were 40s. Four lows were in the colder 30s. 12 lows were in the warmer: 50s (10) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:58 and sunrise was at 5:30. Sunset is at 20:10 and twilight ends at 20:42. There's a total of 14 hours, 40 minutes of daylight today and 15 hours, 44 minutes between twilights. Tomorrow twilight begins at 4:57 and sunrise is at 5:29. The moon is waxing crescent. Illumination was 12% at midnight, will be 16% at noon and 21% at midnight tonight. Moonrise was at 8:33 this morning. Moonset is at a minute past midnight tonight. Moonrise is at 9:46 tomorrow morning. Moonlight time is 15 hours, 27 minutes which is 23 minutes shorter than yesterday.

National Maritime Day is in five days. - Bernie -