April 22: ORD

Today is April 22nd. It's the 113th day of the year. 253 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. Before this, the official site of record was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 62 and the normal low is 41. I've calculated the 33-year averages at 61 and 41.

On the warm side, in 1980 the high was the record high of 91 with a low of 58, a 33 degree spread. Five years later, in 1985, the high was 83 with the record warmest low of 66. The former record warmest low of 62 occurred way back in 1885. 1980 and 1985 are tied as O'Hare's warmest April 22nd days. In 2007 the high was 83 with a low of 52, a 31 degree spread. Six years before that, in 2001, the high was 78 with a low of 51. The other warm high was 74 in 2008. 21 of the past 33 highs (64%) were in the: 50s (9) and 60s (12). O'Hare recorded eight consecutive highs in the 50s & 60s from 1993 through 2000. Our most recent 50s high was 54 in 2004. On the warm side, six highs (18%) were in the: 70s (3), 80s (2) and 90s (1). O'Hare's third warmest April 22nd was in 1960 as the high was 85 with a low of 57. That high of 85 remains as O'Hare's second warmest high of the date. On the cold side, six highs (18%) were in the 40s. 

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 59 with a cold low of 28, a 31 degree spread. In 1977 the high was 52 with a low of 47, a five degree spread. In 1972 the high was a cold 47 degrees. In 1970 the high was 72 with a low of 40, a 32 degree spread. In 1963 the high was a cold 47 degrees. In 1960 the high was 85 with a low of 57, a warm day. In 1959 the high was 63 with a low of 30, a 33 degree spread.

More recently, we had additional small spreads of six degrees in 1987 (50/44) and seven degrees in 1999 (51/44). The additional large spreads were 36 degrees in 1990 (73/37), 34 degrees in 2000 (65/31) and 31 degrees in 1991 (63/32).
 
On the cold side, in 1986 (O'Hare's coldest April 22nd) the high was 47 with the record low of 24. Two years earlier, in 1984, the high was 43 with a low of 36, a seven degree spread. In 2002 the high was 43 with a low of 36, a seven degree spread. Those highs of 43 were O'Hare's coldest highs of the date. Note that 1984 and 2002 had the same temperatures and are the second coldest April 22nd days in O'Hare's history. The other cold highs were 46 in 2005, 46 last year (in 2011), 49 in 1992 and 50 in 1987. The record coldest high of 38 was set back in 1936 at the University of Chicago. 27 of the last 33 lows (82%) were in the: 30s (16) and 40s (11). One low was in the cold 20s (the record low of 24 in 1986). The only other 20s low occurred in the year prior to 1979 (28 in 1978). Five lows were in the warm: 50s (4) and 60s (1).

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. The first instance was a back-to-back-to-back instance: In 1984 the high was 43 with a low of 36, overall 11.5 degrees BELOW normal. Then in 1985 the high was 83 with a low of 66, overall 23.5 degrees ABOVE normal. Then in 1986 the high was 47 with a low of 24, overall 15.5 degrees BELOW normal. In the second instance, in 2001 the high was 78 with a low of 51, overall 13.5 degrees ABOVE normal. Then in 2002 the high was 43 with a low of 36, overall 11.5 degrees BELOW normal.

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 5:30 and sunrise is at 5:59. The moon is waxing crescent, having passed new yesterday at 2:18. Illumination was 1% at midnight, will be 2% at noon and 3% at midnight tonight. Moonrise was at 6:31 this morning. Moonset was at 21:22 tonight. Moonrise is at 7:08 tomorrow morning. Moonlight time is 14 hours, 51 minutes which is 24 minutes longer than yesterday. 

Spring began on March 12th and runs for 84 days through June 3rd. Warm Spring began on April 13th and runs for 52 days through June 3rd. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 80s and 90s occur infrequently. Earth Day is today. Arbor Day is in five days.