March 27: ORD

Today is March 27th. It's the 87th day of the year. 279 days remain. It's week 13 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. Before this, the official site of record was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 51 and the normal low is 33. I've calculated the 33-year averages at 52 and 33.

On the warm side, in 1989 (O'Hare's warmest March 27th) the high was 75 with the record warmest low of 59. In 1998 the high was 77 (O'Hare's warmest high of the date) with a low of 56. Way back in 1910 the low was also 56. These were the former record warmest lows. In 1985 the high was 70 with a low of 54. In 1997 the high was 75 with a low of 48. In 2007 the high was 73 with a low of 45. In 1991 the high was 74 with a low of 38, a 36 degree spread. In 2003 the high was 67 with a low of 40. The record high of 82 was set back in 1945 at Midway. 19 of the past 33 highs (58%) were in the: 40s (9) and 50s (10). On the warm side, eight highs (24%) were in the: 60s (2) and 70s (6). The 60s highs occurred in the back-to-back years of 2003 (67 degrees) and 2004 (60 degrees). On the cold side, six highs (18%) were in the 30s.

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 62 with a warm low of 54, a warm day. In 1975 the high was a cold 34 with a low of 31, a three degree spread. In 1974 the high was 41 with a low of 34, a seven degree spread. In 1970 the high was a cold 39 degrees. In 1969 the low was a cold 19 degrees. In 1968 the high was 76 with a low of 54, a warm day. In 1966 the high was 38 with a low of 20, a cold day. In 1965 the high was 32 with a low of -1, a 33 degree spread and cold day. That low of -1 was colder than the record low (see below). In 1964 the high was 36 with a low of 14, another cold day. In 1963 the high was a warm 67 with a low of 35, a 32 degree spread. In 1961 the high was a warm 67 degrees.

More recently, we had small spreads of six degrees in 1984 (39/33) and seven degrees in 1995 (45/38). There was a large spread of 33 degrees in 1999 (57/24).

On the cold side, in 1996 (O'Hare's second coldest March 27th) the high was 36 with the record low of 12. In 1982 the high was 36 with a low of 20. Three years before that, in 1979, the high was 39 with a low of 18. Last year, in 2011, the high was 35 with a low of 23. The other cold highs were 39 degrees in both 1984 and 2001. The record coldest high of 26 was set way back in 1904, at a time when the official readings were taken adjacent to Lake Michigan. 24 of the last 33 lows (73%) were in the: 20s (11) and 30s (13). O'Hare recorded six consecutive 20s & 30s lows from 1990 through 1995. Two lows (6%) were in the cold 10s (a.k.a. teens). O'Hare's coldest March 27th was in 1965 as the high was 32 with a low of -1. O'Hare's third coldest was in 1964 as the high was 36 with a low of 14. Seven lows (21%) were in the warmer: 40s (4) and 50s (3).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1996 the high was 36 with a low of 12, overall 18 degrees BELOW normal. Then in 1997 the high was 75 with a low of 48, overall 19.5 degrees ABOVE normal.

Today is a major day in Chicago's snow history. In 1970 at O'Hare, this was the fourth of five days in which 11.8 inches fell. Today 0.1 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:16 and sunrise is at 6:44. Sunset is at 19:14 and twilight ends at 19:42. There's a total of 12 hours, 30 minutes of daylight today and 13 hours, 26 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:14 and sunrise is at 6:42. The moon is waxing crescent. Illumination was 18% at midnight, will be 22% at noon and 26% at midnight tonight. Moonrise is at 9:09 this morning. Moonset is at 0:23 tomorrow morning. Moonrise is at 9:53 tomorrow morning. Moonlight time is 14 hours, 51 minutes which is 8 minutes shorter than yesterday.

Spring began on March 12th and runs for 84 days through June 3rd. Cool Spring began on March 12th and runs for 32 days through April 12th. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 60s and 70s usually occur infrequently. April Fools' Day and Palm Sunday are in five days. Good Friday is in ten days. Easter Sunday is in 12 days.