March 23: ORD

Today is March 23rd. It's the 83rd day of the year. 283 days remain. It's week 12 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 50 and the normal low is 31. I've calculated the 33-year averages at 52 and 31.

On the warm side, in 1994 (O'Hare's warmest March 23rd) the high was 74 (O'Hare's warmest high of the date) with a low of 49. Six years earlier, in 1988, the high was 68 with a low of 45. In 1979 the high was 62 with a low of 50 (O'Hare's warmest low of the date). The record warmest low of 50 occurred in 1936. Since O'Hare was not the official station of record in 1979, this low of 50 is not the record warmest low. In 1987 the high was 67 with a low of 40. In 2003 the high was 63 with a low of 41. The other warm high was 62 in 2000. The other warm low was 44 in 2007. The record high of 80 was set way back in 1907. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 29 of the past 33 highs (88%) were in the: 40s (10), 50s (11) and 60s (8). Our most recent 60s high was 60 in 2004. On the warm side, one high was in the 70s. O'Hare's pre-1979 warm highs are 72 in 1963, 66 in 1969 and 65 in 1959. On the cold side, three highs 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 1974 the high was 25 with a low of 12, a cold day. In 1972 the high was a cold 36 degrees. In 1971 the high was a cold 31 with a low of 20, a cold day. In 1969 the high was 66 with a low of 43, a warm day. In 1966 the high was 60 with a low of 27, a 33 degree spread. In 1965 the high was 28 with a low of 8, the coldest March 23 day ever at O'Hare. In 1963 the high was a warm 72 with a low of 30, a 42 degree spread. In 1961 the high was 43 with a low of 36, a seven degree spread. In 1960 the high was 30 with a low of 15, cold day. In 1959 the high was a warm 65 with a low of 32, a 33 degree spread.

More recently, we had small spreads of six degrees in 1985 (44/38) and six degrees in 1993 (42/36). There were large spreads of 37 degrees in 1981 (60/23), 31 degrees in 1999 (53/22) and 31 degrees last year in 2010 (59/28).

On the cold side, in 1983 the high was 32 with a low of 13. In 1990 the high was 38 with a low of 23. The other cold low was 17 in 1992. The other cold high was 38 in 1997. The record low of 9 and record coldest high of 21 were set on the same cold day back in 1940, at a time when the official readings were taken adjacent to Lake Michigan. 25 of the last 33 lows (76%) were in the: 20s (14) and 30s (11). O'Hare recorded eight consecutive 20s & 30s lows from 1995 through 2002. Two lows (6%) were in the cold 10s (a.k.a. teens). Six lows (18%) were in the warm: 40s (5) and 50s (1). O'Hare's coldest March 23rd days were: in 1965 with a high of 28 (one of O'Hare's two 20s highs of the date) and low of 8 (O'Hare's only single digit low of the date) AND in 1974 with a high of 25 (the other 20s highs of the date) and low of 12.

Today is a major day in Chicago's snow history. At O'Hare in 1965, this was the fourth of seven days in which a total of 10.2 inches fell. Today 4.9 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:23 and sunrise is at 6:51. Sunset is at 19:10 and twilight ends at 19:38. There's a total of 12 hours, 19 minutes of daylight today and 13 hours, 15 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:21 and sunrise is at 6:49. The moon is waxing crescent and was new yesterday morning at 9:37. Illumination was 1% at midnight, will be 1% at noon and 3% at midnight tonight. Moonrise is at 6:57 this morning. Moonset is at 20:35 tonight. Moonrise is at 7:25 tomorrow morning. Moonlight time is 13 hours, 38 minutes which is 34 minutes longer 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 nine days.