March 24: ORD

Today is March 24th. It's the 84th day of the year. 282 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 32. I've calculated the 33-year averages at 52 and 32.

On the warm side, three years ago, in 2009, the high was 69 with a low of 48. In 2003 the high was 74 with a low of 42, a 32 degree spread. Four years later, in 2007, the high was 64 with a low of 52 (O'Hare's warmest low of the date). In 1987 the high was 69 with a low of 45. In 2000 the high was 68 with a low of 46. In 1988 the high was 71 with a low of 42. In 2004 the high was 63 with a low of 44. The other warm highs were 64 in 1989, 63 in 1996 and 62 in 1994. The record high of 79 was first set back in 1910 and tied in 1939. The record warmest low of 61 was set back in 1910. So overall, 1910 was our warmest March 24th. These records were set at a time when the official readings were taken adjacent to Lake Michigan. 26 of the past 33 highs (79%) were in the: 40s (8), 50s (10) and 60s (8). On the warm side, two highs (6%) were in the 70s. O'Hare's warmest March 24th was in 1963 (high of 74, low of 47). O'Hare's second warmest March 24th was in 1976 (high of 70, low of 49). Another pre-1979 warm day was in 1959 (high of 74, low of 38). So O'Hare's warmest highs of the date were 74 degrees in 1959, 1963 and 2003. On the cold side, five highs (15%) 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 1978 the high was a cold 33 with a low of 24, a cold day. In 1976 the high was 70 with a low of 49, a warm day. In 1975 the high was 58 with a low of 28, a 30 degree spread. In 1974 the high was 15 with a low of 5, a very cold day and the year that the records were established (at Midway, see "cold side" below). In 1972 the high was a cold 35 with a low of 28, a seven degree spread. In 1971 the high was 37 with a low of 18, a cold day. In 1966 the high was 27 with a low of 18, a cold day. In 1965 the high was 23 with a low of 5, a cold day. In 1963 the high was 74 with a low of 47, a warm day. In 1960 the high was 27 with a low of 13, a cold day. In 1959 the high was a warm 74 with a low of 38, a 36 degree spread and warm day.

More recently, we had a small spread of seven degrees in 1985 (42/35). There were large spreads of 32 degrees in 1989 (64/32) and 33 degrees in 1992 (58/25).

On the cold side, in 1983 the high was 31 with a low of 18. In 2001 the high was 36 with a low of 21. A decade later (and last year) the high was 34 with a low of 24. The other cold high was 38 in 1990. The record low of 5 and record coldest high of 17 were set on the same cold day in 1974 at Midway. 25 of the last 33 lows (76%) were in the: 20s (15) and 30s (10). One low (3%) was in the cold 10s (a.k.a. teens). O'Hare's coldest March 24th was in 1974: high of 15 (O'Hare's only high in the 10s of the date) and low of 5. The second coldest March 24th was in 1965: high of 23 and low of 5. These low of 5 are O'Hare's only single digit lows of the date. O'Hare also had cold highs of 27 in both 1960 and 1966. Seven lows (21%) were in the warm: 40s (6) and 50s (1).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2000 the high was 68 with a low of 46, overall 16 degrees ABOVE normal. Then in 2001 the high was 36 with a low of 21, overall 12.5 degrees BELOW normal.

Today is a major day in Chicago's snow history. At O'Hare in 1965, this was the fifth of seven days in which a total of 10.2 inches fell. Today 0.5 inches fell. In 1970, this was the first of five days in which 11.8 inches fell. Today 0.1 inches fell. In 1930 at the University of Chicago, a total of 21.6 inches fell on the 24th and 25th. 14.4 inches fell in an unspecified 24 hour time frame during these two days. Tom Skilling of WGN-TV said in his blog that the total was 19.2 inches. So there appears to be a slight discrepancy between the totals.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:21 and sunrise is at 6:49. Sunset is at 19:11 and twilight ends at 19:39. There's a total of 12 hours, 22 minutes of daylight today and 13 hours, 18 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:19 and sunrise is at 6:47. The moon is waxing crescent and was new two mornings ago at 9:37. Illumination was 3% at midnight, will be 4% at noon and 6% at midnight tonight. Moonrise is at 7:25 this morning. Moonset is at 21:34 tonight. Moonrise is at 7:56 tomorrow morning. Moonlight time is 14 hours, 9 minutes which is 31 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 eight days.