May 29: ORD

Today is May 29th. It's the 149th day of the year. 216 days remain. It's week 22 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 75 and the normal low is 52. I've calculated the 31-year averages at 75 and 53.

On the warm side, in 2006 the high was 91 degrees with a low of 68. In 1991 the high was 87 with the only 70s low and record warmest low of 71. The former record warmest low was 70 in 1962. In 1987 the high was 89 with a low of 66. In 1999 the high was 86 with a low of 65. Other 80s highs of note were 89 in 1988 and 88 three years ago. The record high of 95 was set back in 1942. 29 of the past 31 highs were: 60s (11), 70s (7) and 80s (11). One high was in the cooler 50s. One high was in the warmer 90s.

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: In 1978 the high was a hot 88 with a low of 63, a hot day. In 1977 the high was 89 with a low of 64, a hot day. In 1973 the high was a cool 55 with a low of 46, a cool day. In 1972 the low was a warm 64. In 1971 the high was 75 with a low of 41, a 34 degree spread. In 1970 the high was 85 with a warm low of 67, a warm day. In 1967 the high was a cool 62. In 1966 the high was 62 with a low of 35, a cool day. In 1965 the high was 55 with a low of 32, a cold day. In 1964 the high was 60 with a low of 36, a cool day. In 1962 the high was 87 with a low of 68, a hot day. 1962 was the year of the record warmest low. In 1961 the high was 62 with a low of 40, a cool day.

More recently, there was a small spread of seven degrees in 1997 (62/55). There were large spreads of 37 degrees in 1979 (82/45), 33 degrees in 1992 (72/39), 31 degrees in 1985 (75/44) and 30 degrees in 1988 (89/59).

On the cool side, 1984 saw the only 50s high of 57 with the record-tying low of 37 (it was also 37 in 1965). In 1996 the high was 60 with a low of 40. Three years earlier, in 1993, the high was 61 with a low of 41. Other cool highs were 62 in 1997, 62 in 2001 and 63 in 1990. Another cool low was 39 in 1992. The record coolest high of 46 was set way back in 1889. 28 of the last 31 lows were: 40s (12), 50s (8) and 60s (8). Two lows were in the colder 30s and one low was in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:48 and sunrise was at 5:21. Sunset is at 20:21 and twilight ends at 20:54. There's a total of 15 hours of daylight today and 16 hours, 6 minutes between twilights. Tomorrow twilight begins at 4:47 and sunrise is at 5:21. The moon is waning gibbous, having reached full two days ago at 18:07. Illumination was 98% at midnight, will be 97% at noon and 95% at midnight tonight. Moonset was at 6:29 this morning. Moonrise is at 22:19 this evening. Moonset is 7:29 tomorrow morning. Moonlight time is 8 hours, 10 minutes which is 7 minutes longer than yesterday.

Memorial Day is in two days. - Bernie -