March 16: ORD

Today is March 16th. It's the 76th day of the year. 290 days remain. It's week 11 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 47 and the normal low is 29. I've calculated the 33-year averages at 47 and 29.

On the warm side, in 2003 the high was 67 with a low of 42. In 1995 the high was 71 with a low of 37, a 34 degree spread. 2003 and 1995, at least through 2011, were O'Hare's warmest March 16ths. Three years ago, in 2009, the high was 65 with a low of 39. In 1990 the high was 62 with a low of 40. The other warm highs were 61 two years ago, in 2010 and 60 last year, in 2011. The record high of 78 and record warmest low of 49 were set on the same warm day back in 1945 at Midway. 27 of the past 33 highs (82%) were in the: 30s (10), 40s (10) and 50s (7). O'Hare's coldest high of the date was 31 in 1960. Our most recent 40s high was 41 in 2002. Our most recent 50s high was 50 in 2005. On the warm side, six highs were in the: 60s (5) and 70s (1). Prior to 1979, O'Hare had warm highs of 66 in 1964, 63 in 1968 and 59 in 1966.

In looking back through the years to the first March at O'Hare in 1959, the following instances were notable: In 1976 the high was a cold 35 degrees. In 1972 the high was 42 with a low of 35, a seven degree spread. In 1971 the high was a cold 32 with a low of 25, a seven degree spread. In 1969 the high was 53 with a low of 22, a 31 degree spread. In 1968 the high was a warm 63 with a low of 33, a 30 degree spread. In 1966 the high was a warm 59 degrees. In 1964 the high was a warm 66 with a low of 27, a 39 degree spread. In 1961 the high was a cold 35 degrees. In 1960 the high was a cold 31 with a low of 24, a seven degree spread.

More recently, we had small spreads of three degrees in 2004 (33/30), four degrees in 2001 (34/30) and six degrees in 2006 (38/32).

On the cold side, in 1997 (O'Hare's coldest March 16th) the high was 37 with a low of 11 (O'Hare's coldest low of the date). Three years earlier, in 1994, the high was 36 with a low of 22. The other cold highs were 33 in 2004 and 34 in 2001. The record low of -1 and record coldest high of 13 were set on the same cold day way back in 1900, at a time when the official readings were taken adjacent to Lake Michigan. 29 of the last 33 lows (88%) were in the: 20s (15) and 30s (14). Two lows were in the cold 10s (a.k.a. teens) and two were in the warm 40s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:35 and sunrise is at 7:03. Sunset is at 19:02 and twilight ends at 19:30. There's a total of 11 hours, 59 minutes of daylight today and 12 hours, 55 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:33 and sunrise is at 7:01. The moon is waning crescent, having reached last quarter two nights ago at 20:25. Illumination was 37% at midnight, will be 32% at noon and 27% at midnight tonight. Moonrise is at 3:27 this morning. Moonset is at 13:16 this afternoon. Moonrise is at 4:08 tomorrow morning. Moonlight time is 9 hours, 49 minutes which is 16 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. St. Patrick's Day is tomorrow.