April 23: ORD

Today is April 23rd. It's the 113th day of the year. 252 days remain. It's week 17 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 61 and the normal low is 40. I've calculated the 32-year averages at 62 and 40.

On the warm side, in 1985 the high was 77 with a low of 59. Five years later, in 1990, the high was 80 with a low of 49, a 31 degree spread. Three years ago, in 2008, the high was 74 with a low of 53. Another warm high was 75 in 1979. The record high of 88 and record warmest low of 66 were set on the same hot day in 1960 at Midway. 27 of the last 32 highs (84%) were in the: 50s (7), 60s (12) and 70s (8). Our most recent 50s high was 56 in 2003. On the warmer side, one high was in the 80s. On the cold side, four highs were in the 40s. Highs over the past five years (2006-10) have been in the 60s and 70s.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1975 the high was a warm 74 degrees. In 1974 the high was a cold 44 with a low of 37, a seven degree spread. In 1971 the high was 68 with a low of 32, a 36 degree spread. In 1969 the high was a cold 49 degrees. In 1967 the high was 43 with a low of 26, a cold day. In 1963 the high was a cold 45 degrees. In 1960 the high was 86 with a low of 66, a hot day and year of the record high and record warmest low, both at Midway.

More recently, we had a small spread of seven degrees in 1988 (47/40). The large spreads were 38 degrees in 1986 (63/25), 34 degrees in 1994 (69/35), 33 degrees in 1979 (75/42), 32 degrees in 1998 (72/40), 31 degrees in 1980 (72/41), 31 degrees in 2006 (72/41), 30 degrees in 1982 (67/37) and 30 degrees in 2009 (67/37).

On the cold side, in 2005 the high was 42 with a low of 35, a seven degree spread. In 1984 the high was 41 with a low of 37, a four degree spread. The other cold low was the record low of 25 in 1986. That record low of 25 was originally set way back in 1873. Other cold highs were 47 in 1988 and 48 in 1999. The record coldest high of 35 was set way back in 1910. 28 of the last 32 lows (88%) were in the: 30s (15) and 40s (13). One low was in the cold 20s (the record low) and three lows were in the warmer 50s.

Today is a major day in Chicago's snow history. In 1967, 3.4 inches fell at O'Hare. Midway had 3.1 inches and Rockford had 3.8 inches.

The recent cold of April 2011: Monday, April 18: high of 41, low of 32. The second coldest April 18 of the past 33 years. Only 1983 (37/23) was colder. Tuesday, April 19: high of 38, low of 34. The second coldest April 19 of the past 33 years. Only 1983 (44/22) was colder. Wednesday, April 20: high of 43, low of 32. The second coldest April 20 of the past 33 years. Only 1981 (41/30) was colder.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:31 and sunrise is at 6:01. Sunset is at 19:43 and twilight ends at 20:13. There's a total of 13 hours, 42 minutes of daylight today and 14 hours, 42 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:29 and sunrise is at 5:59. The moon is waning gibbous and will reach last quarter tomorrow night at 21:47. Illumination was 69% at midnight, will be 64% at noon and 59% at midnight tonight. Moonrise was at 1:01 this morning. Moonset is at 10:36 this morning. Moonrise is at 1:40 tomorrow morning. Moonlight time is 9 hours, 35 minutes which is 16 minutes longer than yesterday.

The warm part of Spring (Warm Spring) began 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. Easter is tomorrow. Administrative Professionals Day is in four days. Arbor Day is in six days. -Bernie-