April 28: ORD

Today is April 28th. It's the 119th day of the year. 247 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 64 and the normal low is 43. I've calculated the 33-year averages at 62 and 40.

On the warm side, in 2003 the high was 77 with a low of 54. In 1993 the high was 73 with a low of 55. The other warm high was 79 in 2004. The record high of 86 was set way back in 1915, at a time when the official readings were taken adjacent to Lake Michigan. The record warmest low of 66 occurred in 1974 at Midway. Another warm low was 63 in 1914. 13 of the past 33 highs (39%) were in the 50s. On the warm side, 17 highs (52%) were in the: 60s (8) and 70s (9). There have been no highs of 80 or higher on this date in O'Hare's history. The warmest highs were 79 degrees, in 1970 and 2004. 1974 was O'Hare's warmest April 28th as the high was 76 with the warmest low of the date, 64 degrees. The second warmest (by just half a degree) was in 1970 with a high of 79 and low of 60. These two 60s lows are the only lows in the 60s for the date. On the cold side, three highs (9%) 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 71 with a low of 37, a 34 degree spread. In 1977 the high was a cold 47 with a low of 32, a cold day. In 1974 the high was 76 with a low of 64, a warm day and day of the record warmest low of 66 at Midway. In 1971 the high was a cold 49 with a low of 42, a seven degree spread. In 1970 the high was 79 with a low of 60, a warm day. In 1968 the high was 69 with a low of 36, a 33 degree spread. In 1967 the high was 62 with a cold low of 30, a 32 degree spread. In 1962 the high was 72 with a low of 41, a 31 degree spread.

More recently, we had an additional small spread of four degrees in 1980 (46/42). We had large spreads of 34 degrees in 2007 (73/39), 33 degrees in 2000 (70/37), 31 degrees in 1981 (73/42), 31 degrees in 1992 (59/28), 31 degrees in 1997 (66/35), 31 degrees in 2004 (79/48), 31 degrees in 2006 (68/37) and 31 degrees two years ago in 2010 (64/33).

On the cold side, in 2008 (O'Hare's second coldest April 28th) the high was 46 with a low of 35. Last year, in 2011, the high was 45 (O'Hare's coldest high of the date) with a low of 40, a five degree spread. The other cold lows were the record low of 28 in 1992 and 31 in 1982. The other cold highs were 46 in 1980, 50 in 1979, 50 in 1996, 51 in 1994 and 51 three years ago in 2009. The record coldest high of 39 occurred way back in 1874, at a time when the official readings were taken adjacent to Lake Michigan. 29 of the last 33 lows (88%) were in the: 30s (14) and 40s (15). One low was in the cold 20s (the record low). Three lows were in the warm 50s. O'Hare's coldest April 28th was in 1977 as the high was 47 with a low of 32. O'Hare also had a cold low of 30 in 1967.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:22 and sunrise is at 5:52. Sunset is at 19:50 and twilight ends at 20:20. There's a total of 13 hours, 58 minutes of daylight today and 14 hours, 58 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:20 and sunrise is at 5:51. The moon is waxing crescent, heading towards first quarter tomorrow at 4:57. Illumination was 38% at midnight, will be 43% at noon and 48% at midnight tonight. Moonset is at 1:15 this morning. Moonrise is at 11:32 this morning. Moonset is at 1:50 tomorrow morning. Moonlight time is 13 hours, 43 minutes which is 25 minutes shorter 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. May Day is in three days. Mother's Day is in 15 days.