April 27: ORD

Today is April 27th. It's the 117th day of the year. 248 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 41. I've calculated the 32-year averages at 61 and 41.

On the warm side, in 1986 the high was the record high of 87 with a low of 61. Four years later, in 1990, the high was 84 with a low of 62. In 1984 the high was 80 with a low of 56. In 1991 the high was 71 with a low of 58. Other warm highs were 79 in 1981 and 75 in 2003. The record warmest low of 67 occurred back in 1915. 12 of the last 32 highs (37%) were in the 50s. On the warmer side, 15 highs (47%) were in the: 60s (6), 70s (6) and 80s (3). Our most recent 60s high was 63 in 2001. On the cold side, five highs (16%) were in the 40s. Our most recent 40s high was 47 in 1992. In the last nine years (2002-10), six highs were in the 50s and three were in the 70s.

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 66 with a low of 35, a 31 degree spread. In 1977 the high was a warm 81 with a low of 44, a 37 degree spread. In 1976 the high was a cold 49 with a low of 32, a cold day. In 1974 the high was a warm 82 with a low of 55, a warm day. In 1971 the high was a cold 48 degrees. In 1970 the high was 77 with a low of 60, a warm day. In 1969 the low was a warm 55 degrees. In 1966 the high was a cold 43 with a low of 37, a six degree spread and cold day. In 1965 the high was 63 with a low of 32, a 31 degree spread. In 1964 the high was 63 with a warm low of 58, a five degree spread. In 1962 the high was 84 with a low of 66, a warm day. In 1959 the high was a cold 47 with a low of 40, a seven degree spread.

More recently, we had small spreads of five degrees in 1980 (45/40) and seven degrees in 1999 (53/46). We had large spreads of 40 degrees in 1981 (79/39), 39 degrees in 2003 (75/36), 33 degrees in 2006 (71/38), 32 degrees in 1994 (69/37), 32 degrees in 1993 (66/34) and 30 degrees in 2000 (68/38).

On the cold side, in 1992 the high was 47 (our most recent 40s high) with a low of 31. Four years earlier, in 1988, the high was 42 with a low of 36, a six degree spread. Other cold highs were 45 in 1980, 47 in 1979, 48 in 1985, 50 in 1982 and 51 last year (in 2010). The record low of 29 was set in 1945 and the record coldest high of 39 occurred in 1934. 27 of the last 32 lows (84%) were in the: 30s (17) and 40s (10). Five lows were in the warmer: 50s (3) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight is at 5:25 and sunrise is at 5:55. Sunset is at 19:48 and twilight ends at 20:18. There's a total of 13 hours, 53 minutes of daylight today and 14 hours, 53 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:23 and sunrise is at 5:53. The moon is waning crescent, having reached last quarter three nights ago at 21:47. Illumination was 30% at midnight, will be 26% at noon and 22% at midnight tonight. Moonrise is at 3:05 this morning. Moonset is at 14:44 this afternoon. Moonrise is at 3:28 tomorrow morning. Moonlight time is 11 hours, 39 minutes which is 34 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. Administrative Professionals Day is today. Arbor Day is in two days. -Bernie-