March 4: ORD

Today is March 4th. It's the 64th day of the year. 302 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. 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 42 and the normal low is 26. I've calculated the 33-year averages at 42 and 25.

On the warm side, in 1983 (O'Hare's warmest March 4th) the high was the record high of 73 with the record warmest low of 50. In 1992 the high was 64 with a low of 35. In 2000 the high was 62 with a low of 29, a 33 degree spread. The other warm high was 54 last year, in 2011. The other warm low was 38 in 2004. 26 of the past 33 highs (79%) were in the: 30s (12) and 40s (14). O'Hare recorded three sets of consecutive highs in the 30s & 40s as follows: six years from 1986 through 1991, seven years from 1993 through 1999 and eight years from 2003 through 2010. On the warm side, five highs were in the: 50s (2), 60s (2) and 70s (1). Prior to 1979, O'Hare had warm highs of 60 in 1968, 55 in 1970 and 54 in 1961. On the cold side, two highs were in the: 10s (a.k.a. teens) (1) and 20s (1). The pre-1979 cold highs were 18 in 1978 and 19 in 1960.

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 18 with a low of 3, a cold day. In 1975 the low was a cold 13 degrees. In 1974 the low was a warm 39 degrees. In 1972 the low was a cold 14 degrees. In 1970 the high was a warm 55 degrees. In 1968 the high was a warm 60 with a low of 27, a 33 degree spread. In 1967 the high was 32 with a low of 26, a six degree spread. In 1963 the high was 38 with a low of 33, a five degree spread. In 1962 the high was a cold 29 degrees. In 1961 the high was 54 with a low of 37, a warm day. In 1960 the high was 19 with a low of 7, a cold day.

More recently, we had small spreads of three degrees in 1993 (36/33), five degrees in 1981 (37/32) and six degrees in 2004 (44/38).

On the cold side, in 2002 (O'Hare's coldest March 4th) the high was 19 with a low of -7. In 2007 the high was 31 with a low of 14. In 1982 the high was 27 with a low of 18. The other cold low was 10 in 1996. The record low of -12 was set way back in 1873. The record coldest high of 17 occurred way back in 1890. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 19 of the last 33 lows (58%) were in the 20s. There were eight consecutive lows in the 20s from 1984 through 1991. Five lows (15%) were in the cold: negative single digits (1) and 10s (a.k.a. teens) (4). O'Hare's single digit lows occurred prior to 1979: 3 in 1978 and 7 in 1960. Nine lows (27%) were in the warm: 30s (8) and 50s (1). Prior to 1979, O'Hare had a warm low of 39 in 1974. There have been no lows in the warm 40s.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1982 the high was 27 with a low of 18, overall 11.5 degrees BELOW normal. Then in 1983 the high was 73 with a low of 50, overall 27.5 degrees ABOVE normal.

Today is a major day in Chicago's snow history. In 2002, 0.3 inches fell. This was the fourth of four days in which a total of 10.2 inches fell. This comprised 91% of the month's total of 11.2 inches. In 1982, 8.5 inches fell. This was the third of three days in which 12.1 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:55 and sunrise is at 6:23. Sunset is at 17:48 and twilight ends at 18:16. There's a total of 11 hours, 25 minutes of daylight today and 12 hours, 21 minutes between twilights. We gained four minutes of daylight from yesterday. Tomorrow twilight begins at 5:53 and sunrise is at 6:21. The moon is waxing gibbous. Illumination was 80% at midnight, will be 84% at noon and 88% at midnight tonight. Moonset is at 3:47 this morning. Moonrise is at 13:56 this afternoon. Moonset is at 4:23 tomorrow morning. Moonlight time is 13 hours, 51 minutes which is 23 minutes shorter than yesterday.

Winter began December 1st and runs for 102 days through March 11th. High temperatures in this period are usually in the 20s and 30s. Highs in the 40s and 50s occur infrequently. St. Patrick's Day is in 13 days.