May 4: ORD

Today is May 4th. It's the 124th day of the year. 241 days remain. It's week 18 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 66 and the normal low is 43. I've calculated the 31-year averages at 66 and 44.

On the warm side, in 2000 the high was 81 with a low of 63. In 1981 the high was 78 with a low of 59. A year earlier, in 1980, the high was 86 with a low of 49, a 37 degree spread. A couple of years later, in 1982, the high was 83 with a low of 51, a 32 degree spread. In 1999 the high was 81 with a low of 53. The record high of 92 occurred in 1952 and the record warmest low of 66 occurred three years later in 1955. 21 of the last 31 highs were: 50s (8) and 60s (13). On the warmer side, nine highs were: 70s (5) and 80s (4). One high was in the cooler 40s.

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 cold 51. In 1976 the high was 68 with a low of 36, a 32 degree spread. In 1969 the high was a warm 83 with a low of 52, a 31 degree spread and warm day. In 1967 the high was a cold 43 with a low of 33, a cold day. In 1966 the high was 62 with a low of 32, a 30 degree spread. In 1964 the high was 82 with a low of 60, a warm day. In 1962 the high was 83 with a low of 55, a warm day. In 1960 the high was 80 with a low of 54, another warm day. In 1959 the high was 90 with a low of 64, a hot day.

More recently, we had a small spread of six degrees in 1990 (49/43). The large spreads were 35 degrees in 2002 (69/34) and 30 degrees in 1994 (66/36).

On the cool side, there have been no days of a mean that was at least 12 degrees below normal. However, we have had some cool highs over the years: 49 in 1990, 54 in 1992 and 54 in 1996. The cold lows were 33 in 2005 and 34 in 2002. The record low of 32 was set in 1954. The record coldest high of 41 was set back in 1907. 25 of the last 31 lows were: 30s (11) and 40s (14). Six lows were in the warmer: 50s (5) and 60s (1).

Today is not a major day in Chicago's snow history. Stay tuned for an event that occurred two days from now and 21 years ago!

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:14 and sunrise was at 5:45. Sunset is at 19:56 and twilight ends at 20:27. There's a total of 14 hours, 11 minutes of daylight today and 15 hours, 13 minutes between twilights. Tomorrow twilight begins at 5:13 and sunrise is at 5:44. The moon is waning gibbous. Illumination was 68% at midnight, will be 64% at noon and 59% at midnight tonight. Moonrise was at 1:03 early this morning. Moonset was at 10:45. Moonrise is at 1:34 early tomorrow morning. Moonlight time is 9 hours, 42 minutes which is 25 minutes longer than yesterday.

National Teacher Day is today. Mother's Day is in five days. - Bernie -