March 12: ORD

Today is March 12th. It's the 71st day of the year. 294 days remain. It's week 11 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 44 and the normal low is 27. I've calculated the 32-year averages at 45 and 26.

On the warm side, in 1990 the high was the record high of 81 with the record warmest low of 59. Five years later, in 1995, the high was 71 with a low of 41, a 30 degree spread. In 1982 the high was 60 with a low of 36. In 2006 the high was 56 with a low of 40. Last year, in 2010, the high was 55 with a low of 40. Other warm highs were 63 in 2007, 60 in 1981, 57 in 1994 and 56 in 1988. 23 of the last 32 highs (72%) were in the: 30s (9), 40s (8) and 50s (6) . On the warmer side, five highs were in the: 60s (3), 70s (1) and 80s (1). On the cold side, four highs were in the 20s. Today is the mode date (or most frequent date) for our first high in the 60s based upon the past 32 years.

In looking back through the years to the first March at O'Hare in 1959, the following instances were notable: In 1977 the high was 69 with a low of 43, a warm day. In 1976 the high was a warm 60 degrees. In 1969 the low was a cold 11 degrees. In 1967 the high was 38 with a low of 33, a five degree spread. In 1966 the low was a warm 40 degrees. In 1965 the high was 34 with a low of 29, a five degree spread. In 1962 the high was 37 with a low of 33, a four degree spread. In 1960 the high was 33 with a cold low of 10, a cold day.

More recently, we had small spreads of four degrees in 1991 (34/30), six degrees in 1989 (39/33) and seven degrees in 1986 (39/32). The other large spreads were 30 degrees in 1981 (60/30) and 37 degrees in 2007 (63/26).

On the cold side, in 1998 the high was 26 with a low of 10. In 1984 the high was 24 with a low of 13. Two years ago, in 2009, the high was 26 with a low of 14. In 1993 the high was 31 with a low of 11. A year earlier, in 1992, the high was 29 with a low of 15. In 2004 the high was 33 with a low of 16. In 1980 the high was 30 with a low of 19. Another cold low was 15 in 1979. The record low of 1 was set in 1948. The record coldest high of 14 occurred way back in 1896. 28 of the last 32 lows (88%) were in the: 10s (a.k.a. teens) (11), 20s (7) and 30s (10). Our most recent 30s low was 30 in 2001. On the warmer side, three lows were in the 40s and one was in the 50s (the record warmest low of 59 in 1990).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:43 and sunrise is at 6:11. Sunset is at 17:56 and twilight ends at 18:24. There's a total of 11 hours, 45 minutes of daylight today and 12 hours, 41 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:41 and sunrise is at 7:09. The moon is waxing crescent and reaches first quarter today at 17:45. Illumination was 43% at midnight, will be 48% at noon and 53% at midnight tonight. Moonset was at 0:54 early this morning. Moonrise is at 10:07 this morning. Moonset is at 2:48 tomorrow morning. Moonlight time is 14 hours, 47 minutes which is five minutes longer than yesterday.

St. Patrick's Day is in five days. The cool part of Spring (Cool Spring) begins today. Cool Spring runs for 32 days, through April 12. High temperatures in this period are usually in the 30s, 40s and 50s. Warmer 60s and 70s occur infrequently. -Bernie-