April 11: ORD

Today is April 11th. It's the 101st day of the year. 264 days remain. It's week 15 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 56 and the normal low is 36. I've calculated the 32-year averages at 56 and 37.

On the warm side, in 2005 the high was 76 with a low of 53. Four years before, in 2001, the high was 77 with a low of 51. Five years before, in 1996, the high was 82 with a low of 45, a 37 degree spread. In 2002 the high was 75 with a low of 50. Four years later, in 2006, the high was 75 with a low of 48. Other warm highs were 70 in 2003 and 69 in 1981. The record high of 90 was set back in 1930. The record warmest low of 60 was set in 1977. 24 of the last 32 highs (75%) were in the: 40s (11), 50s (6) and 60s (7). Our most recent 50s high was 51 in 1999. On the warmer side, six highs were in the: 70s (5) and 80s (1). All of the 70s highs occurred in a six year span from 2001 and 2006. On the colder side, two highs were in the 30s. The 30s highs happened fairly close in years, one in 1997 and one in 2000.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1977 the high was 84 with a low of 59, a warm day and year of the record warmest low. In 1976 the high was a cold 41 degrees. In 1974 the low was a warm 50 degrees. In 1971 the high was a warm 80 with a low of 47, a 33 degree spread and warm day. In 1968 the high was a warm 74 with a low of 39, a 35 degree spread. In 1965 the high was 75 with a low of 49, a warm day. In 1964 the high was a warm 76 with a low of 41, a 35 degree spread and warm day. In 1959 the high was a cold 44 degrees.

More recently, we had large spreads of 32 degrees in 1998 (66/34), 35 degrees in 1986 (66/31) and 38 degrees in 2003 (70/32). There were no small spreads other than in 1997 (see next section).

On the cold side, in 1997 the high was 35 with a low of 32, a three degree spread. In 2000 the high was 39 with a low of 29. Another cold low was the record low of 25 in 1989. Two other years share the record low of 25: 1973 and way back in 1882. Other cold highs were 40 in 1990, 43 in 2004, 43 in 2007 and 44 in 1991. The record coldest high of 33 was set way back in 1882. So since 1882 has both the record low and record coldest high, it's the coldest April 11. 25 of the last 32 lows (78%) were in the: 30s (16) and 40s (9). Four lows were in the cold 20s. Three lows were in the warmer 50s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:51 and sunrise is at 6:20. Sunset is at 19:30 and twilight ends at 19:59. There's a total of 13 hours, 10 minutes of daylight today and 14 hours, 8 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:49 and sunrise is at 6:18. The moon reaches first quarter today at 7:05. Illumination was 47% at midnight, will be 53% at noon and 58% at midnight tonight. Moonset was at 2:13 this morning. Moonrise is at 12:05 this afternoon. Moonset is at 2:51 tomorrow morning. Moonlight time is 14 hours, 8 minutes which is 23 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) begins in two days 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. Palm Sunday is in six days. -Bernie-