March 5: ORD

Today is March 5th. It's the 65th day of the year. 301 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 41 and 27.

On the warm side, in 1983 (O'Hare's warmest March 5th) the high was the record high of 75 with the record warmest low of 56, a huge 31.5 degrees above normal. In 1992 the high was 63 with a low of 43. In 2000 the high was 69 with a low of 34, a 35 degree spread. Three years ago, in 2009, the high was 65 with a low of 36. Five years before that, in 2004, the high was 61 with a low of 39. 17 of the past 33 highs (52%) were in the 30s. On the warm side, 12 highs (36%) were in the: 40s (4), 50s (3), 60s (4) and 70s (1). The more recent 50s highs (51 in 1987, 52 in 1991 and 51 in 1994) occurred in 3 of 8 years from 1987 through 1994. These 50s highs were not significantly above normal. However, three significant ones occurred prior to 1979. They are 57 in 1974, 55 in 1968 and 55 in 1976. Interestingly, O'Hare recorded no 60s highs prior to 1992. On the cold side, four highs (12%) were in the 20s.

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 23 with a low of -3, a cold day and year of the record low (0 at Midway). In 1977 the high was 38 with a low of 31, a seven degree spread. In 1976 the high was a warm 55 degrees. In 1974 the high was a warm 57 with a low of 35, a warm day. In 1972 the high was 22 with a low of 7, a cold day. In 1968 the high was a warm 55 degrees. In 1967 the high was 35 with a low of 29, a six degree spread. In 1966 the high was a cold 30 degrees. In 1963 the high was 34 with a low of 32, a mere two degree spread. In 1962 the high was a cold 26 with a low of 19, a seven degree spread and cold day. In 1960 the high was 20 with a low of 0, a cold day.

More recently, we had small spreads of three degrees in 1979 (32/29), four degrees in 1996 (33/29), six degrees in 1990 (36/30), six degrees in 2005 (41/35), seven degrees in 1995 (38/31) and seven degrees in 1998 (39/32).

On the cold side, in 1982 the high was 34 with a low of 7. In 2003 the high was 24 (our most recent 20s high) with a low of 19, a five degree spread. In 1989 the high was 27 with a low of 17. In 2002 the high was 33 with a low of 12. The other cold highs were 28 in 2001 and 29 in 1985. The record low of 0 was set in 1978 at Midway. This tied the original record of 0 which was set way back in 1873, at a time when the official readings were taken adjacent to Lake Michigan. The record coldest high of 12 occurred way back in 1901, also at a time when the official readings were taken adjacent to Lake Michigan. 30 of the last 33 lows (91%) were in the: 10s (a.k.a. teens) (8), 20s (13) and 30s (9). One low was in the cold single digits. Two lows were in the warm: 40s (1) and 50s (1). O'Hare's coldest days were: 1960's coldest high (of the date) of 20 with low of 0 and 1978's high of 23 with coldest low (of the date) of -3. Both days were 24 degrees below normal.

There was two instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1982 the high was 34 with a low of 7, overall 13.5 degrees BELOW normal. Then in 1983 the high was 75 with a low of 56, overall 31.5 degrees ABOVE normal. In the second instance, in 2003 the high was 24 with a low of 19, overall 12.5 degrees BELOW normal. Then in 2004 the high was 61 with a low of 39, overall 16 degrees ABOVE normal.

Today is a major day in Chicago's snow history. In 1999, 3.8 inches fell. This was the first 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 5:53 and sunrise is at 6:21. Sunset is at 17:49 and twilight ends at 18:17. There's a total of 11 hours, 28 minutes of daylight today and 12 hours, 24 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:52 and sunrise is at 6:20. The moon is waxing gibbous. Illumination was 88% at midnight, will be 91% at noon and 94% at midnight tonight. Moonset is at 4:23 this morning. Moonrise is at 15:04 this afternoon. Moonset is at 4:56 tomorrow morning. Moonlight time is 13 hours, 19 minutes which is 32 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 12 days.