April 5: ORD

Today is April 5th. It's the 95th day of the year. 270 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 54 and the normal low is 34. I've calculated the 32-year averages at 54 and 33.

On the warm side, in 1988 the high was the record high of 85 with a low of 54, a 31 degree spread. Two years earlier, in 1986, the high was 76 with a low of 49. In 2005 the high was 76 with a low of 47. In 1997 the high was 67 with a low of 55. Last year, in 2010, the high was 72 with a low of 50. In 1991 the high was 76 with a low of 45, a 31 degree spread. The record warmest low of 69 occurred back in 1929. 23 of the last 32 highs (72%) were in the: 40s (9), 50s (8) and 60s (6). On the warmer side, five highs were in the: 70s (4) and 80s (1). On the cold side, four highs were in the 30s.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1976 the high was 62 with a low of 31, a 31 degree spread. In 1975 the high was 35 with a low of 18, one of our coldest April 5th days. In 1967 the high was 67 with a low of 49, a warm day. In 1963 the high was 62 with a low of 29, a 33 degree spread. In 1960 the high was a cold 42 degrees.

More recently, we had small spreads of six degrees in both 1983 (41/35) and 1985 (39/33). There were large spreads of 31 degrees in 1995 (49/18), 36 degrees in 1979 (55/19) and 38 degrees in 2000 (63/25).

On the cold side, in 1982 the high was the record coldest high of 31 with a low of 22. Two decades and a year later, in 2003, the high was 33 with a low of 25. In 1996 the high was 39 with a low of 25. In 2002 the high was 41 with a low of 24. Other cold lows were the record low of 18 in 1995 and a low of 19 in 1979. The low was also 18 in 1979 at Midway, so Midway shares the record low today with O'Hare. Other cold highs were 39 in 1985, 40 in 2007, 41 in 1983 and 42 in 1981. The former record coldest high of 32 occurred way back in 1898. 23 of the last 32 lows (72%) were in the: 20s (11) and 30s (12). Two lows were in the cold 10s (a.k.a. teens). Seven lows were in the warmer: 40s (4) and 50s (3).

Both 1979 and 1995 were very cold days today. In 1979, area lows were: Rockford: 17, Aurora: 17, Barrington: 9, University of Chicago: 18, DeKalb (NIU): 18, Elgin: 11, Marengo: 8, Joliet: 18, Wheaton: 16, Midway: 18 and O'Hare: 19. In 1995, Rockford: 15, Aurora: 19, Chicago Botanical Gardens: 16, Midway: 23, DeKalb(NIU): 17, Elgin: 16, Lake Villa: 16, Marengo: 15, O'Hare: 18 and Streamwood: 12.

Today is a major day in Chicago's snow history. In 1982, O'Hare had 9.4 inches of snow. This was 89% of it's total of 10.6 inches for the month. Midway had 9.8 inches and Rockford had 6.3 inches. So much for Spring on this day in 1982! In 1938, the city had a tenth of an inch.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:01 and sunrise is at 6:30. Sunset is at 19:23 and twilight ends at 19:52. There's a total of 12 hours, 53 minutes of daylight today and 13 hours, 51 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:59 and sunrise is at 6:28. The moon is waxing crescent and reached new two days ago at 9:32. Illumination was 3% at midnight, will be 4% at noon and 6% at midnight tonight. Moonrise is at 7:05 this morning. Moonset is at 21:50 tonight. Moonrise is at 7:38 tomorrow morning. Moonlight time is 14 hours, 45 minutes which is 32 minutes longer than yesterday.

The warm part of Spring (Warm Spring) begins in eight days on April 13. Warm Spring runs for 52 days, through June 3. High temperatures in this period are usually in the 50s, 60s and 70s. Warmer 80s and 90s occur infrequently. Palm Sunday is in 12 days. -Bernie-