April 28: ORD

Today is April 28th. It's the 118th 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.

According to the National Climatic Data Center (NCDC), the normal high is 63 and the normal low is 42. I've calculated the 32-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. Another warm high was 79 in 2004. The record high of 86 was set back in 1915 and the record warmest low of 66 occurred in 1974. Another warm low was 63 in 1914. 13 of the last 32 highs (41%) were in the 50s. On the warmer side, 17 highs (53%) were in the: 60s (8) and 70s (9). On the cold side, two highs were in the 40s. The last four years have featured each category of high temperature: 73 in 2007, 46 in 2008, 51 in 2009 and 64 in 2010.

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 1963 the low was a warm 54 degrees. In 1962 the high was 72 with a low of 41, a 31 degree spread.

More recently, we had a 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 last year in 2010 (64/33).

On the cold side, three years ago (in 2008) the high was 46 with a low of 35. In 1996 the high was 50 with a low of 36. Two years prior, in 1994, the high was 51 with a low of 35. In 1979 the high was 50 with a low of 36. Another cold low was the record low of 28 in 1992. Other cold highs were 46 in 1980 and 51 two years ago in 2009. The record coldest high of 39 occurred way back in 1874. 28 of the last 32 lows (88%) were in the: 30s (14) and 40s (14). One low was in the cold 20s (the record low). Three lows were in the warmer 50s. Back-to-back years had radically different lows. The record low of 28 in 1992 was followed by our warmest low of 55 in 1993. Still, that low of 55 is 11 degrees cooler than the record warmest low of 66, set in 1974.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight is at 5:23 and sunrise is at 5:53. Sunset is at 19:49 and twilight ends at 20:19. There's a total of 13 hours, 56 minutes of daylight today and 14 hours, 56 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:22 and sunrise is at 5:52. The moon is waning crescent. Illumination was 22% at midnight, will be 18% at noon and 14% at midnight tonight. Moonrise is at 3:28 this morning. Moonset is at 15:43 this afternoon. Moonrise is at 3:51 tomorrow morning. Moonlight time is 12 hours, 15 minutes which is 36 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. Arbor Day is tomorrow. -Bernie-