March 26: ORD

Today is March 26th. It's the 86th day of the year. 280 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 32. I've calculated the 33-year averages at 51 and 32.

On the warm side, in 2007 (O'Hare's warmest March 26th) the high was the record high of 79 with the record warmest low of 63. The former record high of 77 occurred in 1976. The former record warmest lows were 56 in 1976 followed by 60 in 1998. In 1998 the high was 75 with a low of 60. Seven years earlier, in 1991, the high was 75 with a low of 52. In 2004 the high was 67 (our most recent 60s high) with a low of 45. In 1989 the high was 76 with a low of 34, a 42 degree spread. The other warm highs were 68 in 2000, 65 in 1985, 63 in 1986 and 63 in 1981. 28 of the past 33 highs (85%) were in the: 30s (5), 40s (13), 50s (5) and 60s (5). On the warm side, four highs were in the 70s. Prior to 2007, O'Hare's warmest high was 77 in 1976. The other pre-1979 warm highs were 74 in 1968, 72 in 1961, 69 in 1977 and 65 in 1967. On the cold side, one high was in the 20s. Prior to 1979, O'Hare had a cold high of 25 in 1964.

In looking back through the years to the first March at O'Hare in 1959, the following instances were notable: In 1978 the high was a cold 33 with a low of 31, a two degree spread. In 1977 the high was a warm 69 with a low of 38, a 31 degree spread. In 1976 the high was 77 with a low of 53, the former record high and warm day. In 1975 the high was 35 with a low of 20, a cold day. In 1969 the high was a cold 32 with a low of 22, a cold day. In 1968 the high was 74 with a low of 47, a warm day. In 1967 the high was a warm 65 degrees. In 1966 the high was a cold 38 with a low of 23, a cold day. In 1965 the high was 28 with a low of 3, a cold day. That low of 3 was colder than the record low (see below). In 1964 the high was 25 with a low of 18, a seven degree spread and a cold day. In 1961 the high was 72 with a low of 47, a warm day. In 1960 the high was 34 with a low of 11, another cold day. In 1959 the high was a cold 38 with a low of 34, a four degree spread.

More recently, we had an additional small spread of seven degrees in 1987 (49/42). There were large spreads of 34 degrees in 1985 (65/31), 32 degrees in 2000 (68/36) and 30 degrees in 1986 (63/33).

On the cold side, in 1996 the high was the record coldest high of 23 with a low of 15. The record coldest high of 23 also occurred back in 1937. Five years later, in 2001, the high was 33 with a low of 16. In 1979 the high was 33 with a low of 16. Last year, in 2011, the high was 32 with a low of 25. In 1982 the high was 34 with a low of 27. The other cold high was 38 in 2002. The record low of 7 was set way back in 1873, at a time when the official readings were taken adjacent to Lake Michigan. 25 of the last 33 lows (76%) were in the: 20s (9) and 30s (16). O'Hare recorded seven consecutive lows in the 20s & 30s from 1980 through 1986. Three lows (9%) were in the cold 10s (a.k.a. teens). O'Hare's coldest March 26th was in 1965 when the high was 28 with a low of 3, its coldest low of the date. Five lows (15%) were in the warm: 40s (2), 50s (1) and 60s (2).

Today is a major day in Chicago's snow history. At O'Hare in 1965, this was the seventh of seven days in which a total of 10.2 inches fell. Today 0.7 inches fell. In 1970 at O'Hare, this was the third of five days in which 11.8 inches fell. Today 4.8 inches fell. At Midway in 1970, 8.9 inches fell. This was the second of two days in which a total of 14.3 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:17 and sunrise is at 6:45. Sunset is at 19:13 and twilight ends at 19:41. There's a total of 12 hours, 28 minutes of daylight today and 13 hours, 24 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:16 and sunrise is at 6:44. The moon is waxing crescent. Illumination was 12% at midnight, will be 15% at noon and 18% at midnight tonight. Moonrise is at 8:30 this morning. Moonset is at 23:29 tonight. Moonrise is at 9:09 tomorrow morning. Moonlight time is 14 hours, 59 minutes which is 23 minutes longer than yesterday. Moonlight time is at its peak today.
 

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 six days.