April 7: ORD

Today is April 7th. It's the 97th day of the year. 268 days remain. It's week 14 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 55 and the normal low is 35. I've calculated the 31-year averages at 55 and 34.

On the warm side, in 1991 the high was 79 with a low of 60. A decade later, in 2001, the high was the near-record high of 83 with a low of 44, a 39 degree spread. In 1980 the high was 71 with a low of 47. Six years later, in 1986, the high was 79 with a low of 39, a 40 degree spread. Five years before, in 1981, the high was 74 with a low of 43, a 31 degree spread. Another warm high was 77 in 1999. The record high of 84 was set way back in 1893. The record warmest low of 63 was set back in 1929. 16 of the last 31 highs were: 40s (8) and 50s (8). On the warmer side, 11 highs were: 60s (5), 70s (5) and 80s (1). On the colder side, four highs were 30s.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1978 the high was a warm 73 with a low of 45, a warm day. In 1975 the high was a cold 41. In 1972 the high was 33 with a low of 21, a cold day. In 1971 the high was a warm 68 with a low of 30, a 38 degree spread. In 1970 the high was 61 with a low of 30, a 31 degree spread. In 1969 the high was a warm 71 with a low of 38, a 33 degree spread. In 1968 the high was a warm 72 with a low of 40, a 32 degree spread. In 1959 the high was 70 with a low of 51, a warm day.

More recently, we had large spreads of 30 degrees in 1994 (51/21) and 44 degrees in 1999 (77/33).

On the cold side, in 1982 the high was 34 with the record low of 7. Three years ago the high was the record coldest high of 32 with a low of 22. In 1996 the high was 39 with a low of 23. In 2003 the high was 34 with a low of 30, a four degree spread. In 1979 the high was 40 with a low of 24. In 1990 the high was 45 with a low of 22. Another cold low was 21 in 1994. Another cold high was 43 in 1997. 13 of the last 31 lows were 30s. Ten lows were in the colder: single digits (1) and 20s (9). Remarkably, there have been no lows in the 10s (a.k.a. teens). Eight lows were in the warmer: 40s (7) and 60s (1). There have been no lows in the 50s.

1982 had the coldest temperatures. Area lows were: Rockford: 5, Barrington: 5, Chicago Botanical Gardens: 10, Midway: 10, Marengo: 6, Wheaton: 4, Aurora: 8 and Elgin: 11. In northwest Illinois, Mt. Carroll had a low of minus 2.

Today is not a major day in Chicago's snow history.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:57 and sunrise was at 6:26. Sunset is at 19:26 and twilight ends at 19:54. There's a total of 13 hours of daylight today and 13 hours, 57 minutes between twilights. Tomorrow twilight begins at 5:55 and sunrise is at 6:24. The moon is waning crescent and reached last quarter yesterday at 4:37. Illumination was 42% at midnight, will be 37% at noon and 33% at midnight tonight. Moonrise was at 3:06 this morning. Moonset is at 12:57. Moonrise is at 3:34 tomorrow morning. Moonlight time is 9 hours, 51 minutes which is 27 minutes longer than yesterday.

National Tax Freedom Day is in two days. Illinois Tax Freedom Day is in four days. - Bernie -