March 10: ORD

Today is March 10th. It's the 69th day of the year. 296 days remain. It's week 10 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 42 and 24.

On the warm side, last year (in 2010) the high was 62 with a low of 46. That low of 46 was our first 40s low of the past 32 years. In 1990 the high was 62 with a low of 39. Five years before that, in 1985, the high was 64 with a low of 32, a 32 degree spread. Two years ago, in 2009, the high was 61 with a low of 33. Other warm highs were 58 in 1986 and 57 in 1997. The highs are fairly evenly distributed. About half of them, 17 of the 32 or 53% were in the: 40s (5), 50s (8) and 60s (4). On the cold side, 15 of the 32 (47%) were in the: 20s (6) and 30s (9). Highs were in the 60s the past two years. Highs were in the 20s in 2002 and 2003, our most recent 20s highs.

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 67 with a low of 41, a warm day. In 1974 the high was 42 with a low of 35, a seven degree spread. In 1973 the high was 62 with a low of 39, a warm day. In 1972 the low was a cold 15 degrees. In 1970 the high was a cold 31 degrees. In 1967 the high was a warm 60 with a low of 37, a warm day. In 1966 the high was 56 with a low of 39, a warm day. In 1965 the high was a cold 30 degrees. In 1962 the high was 36 with a low of 32, a four degree spread. In 1961 the low was a cold 15 degrees. In 1960 the high was a cold 30 degrees.

More recently, we had a small spread of six degrees in 1983 (30/24). There was another large spread of 32 degrees in 2001 (50/18).

On the cold side, in 2003 the high was 20 with the record low of 2. The former record low of 5 occurred way back in 1892. In 1979 the high was 22 with a low of 9. Five years later, in 1984, the high was 28 with a low of 6. In 1998 the high was 23 with a low of 13. Six years earlier, in 1992, the high was 24 with a low of 15. A decade later, in 2002, the high was 28 with a low of 14. Other cold highs were 30 in both 1983 and 1987. Another cold low was 14 in 1996. 22 of the last 32 lows (69%) were in the: 20s (12) and 30s (10). On the cold side, nine lows (28%) were in the: single digits (3) and 10s (a.k.a. teens) (6). The most recent cold days occurred in the back to back years of 2002 (28/14) and 2003 (20/2). One low (last year's 46) was in the warmer 40s which represents just 3% of the lows.

Today is a major day in Chicago's snow history. In 1999, 1.0 inches fell. This was the sixth of six days in which a total of 18.2 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:46 and sunrise is at 6:14. Sunset is at 17:54 and twilight ends at 18:22. There's a total of 11 hours, 40 minutes of daylight today and 12 hours, 36 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:45 and sunrise is at 6:12. The moon is waxing crescent. Illumination was 24% at midnight, will be 28% at noon and 33% at midnight tonight. Moonrise is at 8:36 this morning. Moonset is at 23:57 tonight. Moonrise is at 9:18 tomorrow morning. Moonlight time is 15 hours, 21 minutes which is 25 minutes longer than yesterday. Moonlight time is at it's peak today.

St. Patrick's Day is in seven days. The cool part of Spring (Cool Spring) begins in two days on March 12. 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-