March 30: ORD

Today is March 30th. It's the 90th day of the year. 276 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 52 and the normal low is 34. I've calculated the 33-year averages at 53 and 35.

On the warm side, in 1998 (O'Hare's warmest March 30th) the high was the co-record high of 79 with the record warmest low of 66. In 2005 the high was 77 with a low of 54. In 1986 the high was the co-record high of 79 with a low of 51. Four years earlier, in 1982, the high was 63 with a low of 48. In 1999 the high was 72 with a low of 38, a 34 degree spread. Two decades earlier, in 1979, the high was 66 with a low of 43. The other warm highs were 70 in 2006, 66 in 1993 and 64 two years ago in 2010. The other warm low was 46 in 2007. 15 of the past 33 highs (45%) were in the 40s. On the warm side, 16 highs (49%) were in the: 50s (6), 60s (5) and 70s (5). O'Hare's third high of 79 for the date occurred on its second warmest March 30th in 1967 (high of 79, low of 53). The other pre-1979 warm highs were 76 in 1968, 75 in 1963 and 65 in 1977. On the cold side, two highs (6%) 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 57 with a low of 27, a 30 degree spread. In 1977 the high was a warm 65 degrees. In 1975 the high was 30 with a low of 21, a cold day. In 1972 the high was a cold 37 with a low of 23, a cold day. In 1969 the high was 27 with a low of 12, a cold day, year of the record low of 12 and record coldest high of 27 (at Midway). In 1968 the high was a warm 76 with a low of 34, a 42 degree spread and warm day. In 1967 the high was 79 (equal to the record high) with a low of 53, another warm day. In 1965 the high was 36 with a low of 20, a cold day. In 1964 the high was 31 with a low of 2, another cold day. That low of 2 was colder than the record low (12 degrees). And of course, it isn't the record because O'Hare was not the official station of record for Chicago in 1964. In 1963 the high was a warm 75 with a low of 41, a 34 degree spread and warm day. In 1961 the low was a cold 20 degrees. 

More recently, we had small spreads of six degrees in 1985 (38/32) and six degrees in 2008 (42/36). There were large spreads of 35 degrees two years ago in 2010 (64/29), 35 degrees in 2006 (70/35) and 32 degrees in 1993 (66/34).

On the cold side, in 1987 the high was 34 with a low of 23. In 1991 the high was 42 with a low of 22. The other cold high was 38 in 1985. The record low of 12 and record coldest high of 27 were set on the same cold day in 1969. 26 of the last 33 lows (79%) were in the: 20s (9) and 30s (17). O'Hare's coldest March 30th was in 1964 with a high of 31 and low of 2. That low of 2 was colder than the official record low and is O'Hare's only single digit low of the date. O'Hare's second coldest March 30th was in 1969 with a high of 27 and low of 12. The high was O'Hare's only 20s high of the date and the low was its only 10s (a.k.a. teens) low of the date. Seven lows (21%) were in the warm: 40s (4), 50s (2) and 60s (1).   

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1986 the high was 79 with a low of 51, overall 22 degrees ABOVE normal. Then in 1987 the high was 34 with a low of 23, overall 14.5 degrees BELOW normal. 

Today is a major day in Chicago's snow history. Today and tomorrow, back in 1926 at the University of Chicago, 8.7 inches fell. Rockford today had 2.5 of it's 16 inch total back in 1926.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:10 and sunrise is at 6:38. Sunset is at 19:17 and twilight ends at 19:46. There's a total of 12 hours, 39 minutes of daylight today and 13 hours, 36 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:09 and sunrise is at 6:37. The moon is reaches first quarter today at 14:41. Illumination was 45% at midnight, will be 49% at noon and 54% at midnight tonight. Moonset was at 1:59 this morning. Moonrise is at 11:39 this morning. Moonset is at 2:40 tomorrow morning. Moonlight time is 14 hours, 20 minutes which is nine minutes shorter 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 two days. Good Friday is in seven days. Easter is in nine days.