February 24: ORD

Today is February 24th. It's the 55th day of the year. 311 days remain. It's week 8 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 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 38 and the normal low is 23. I've calculated the 33-year averages at 38 and 23.

On the warm side, in 2002 the high was 61 with a low of 38. A couple of years earlier, in 2000, the high was 57 with a low of 41, O'Hare's warmest low of the date. Four years before, in 1996, the high was 58 with a low of 34. Two years later, in 1998, the high was 54 with a low of 36. Three years later, in 2001, the high was 56 (our most recent 50s high) with a low of 30. Two decades earlier, in 1981, the high was 53 with a low of 32. The record high of 64 was set in 1930 and the record warmest low of 46 occurred in 1936. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 16 of the past 33 highs (49%) were in the 30s. On the warm side, ten highs (30%) were in the: 40s (4), 50s (5) and 60s (1). O'Hare's warmest February 24th was in 1976 when the high was 63 and low was 38. Another warm high was 51 in 1977. On the cold side, seven highs (21%) were in the: 10s (a.k.a. teens) (1) and 20s (6). O'Hare's coldest high was 9 in 1967.

In looking back through the years to the first February at O'Hare in 1959, the following instances were notable: In 1977 the high was a warm 51 degrees. In 1976 the high was 63 with a low of 38, a warm day. In 1974 the high was a cold 22 with a low of 13, a cold day. In 1967 the high was 9 with a low of -6, a cold day. In 1965 the high was a cold 24 with a low of 19, a five degree spread. In 1964 the high was 29 with a cold low of 4, a cold day. In 1963 the high was 26 with a low of -1, a cold day. In 1962 the high was 29 with a low of 24, a five degree spread. In 1960 the high was 29 with a low of 23, a six degree spread.

More recently, we had small spreads of: four degrees last year, in 2011 (36/32), six degrees in 2004 (37/31), six degrees in 2007 (32/26), seven degrees in 1979 (30/23), seven degrees in 1985 (39/32), seven degrees in 1992 (40/33) and a large spread of 32 degrees in 2006 (47/15).

On the cold side, in 1993 the high was 15 with a low of -5. In 1989 the high was 22 with a low of 4. In 2003 the high was 23 with a low of 6, our most recent single digit low. In 1994 the high was 22 with a low of 8. The other cold low was 7 in 1990. The other cold high was 26 in 1988. The record low of -11 was set way back in 1873 and the record coldest high of 8 occurred way back in 1889. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 21 of the last 33 lows (64%) were in the: 20s (11) and 30s (10). O'Hare recorded 13 consecutive lows in the 20s & 30s from 1975 through 1987. On the cold side, 11 lows (33%) were in the: negative single digits (1), single digits (4) and 10s (a.k.a. teens) (6). 1967 was O'Hare's coldest February 24th as the high was 9 with a low of -6. Both the high and low were the coldest of the date. Another cold low was -1 in 1963. One low (3%) was in the warm 40s.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2002 the high was 61 with a low of 38, overall 18.5 degrees ABOVE normal. Then in 2003 the high was 23 with a low of 6, overall 16.5 degrees BELOW normal.

Today is a major day in Chicago's snow history. In 1994, 0.3 inches fell. This was the third of four days in which 16.1 inches fell. In 1965, 6.7 inches fell. This was the second of three days in which 10 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:09 and sunrise is at 6:37. Sunset is at 17:37 and twilight ends at 18:05. There's a total of 11 hours of daylight today and 11 hours, 56 minutes between twilights. We gained four minutes of daylight from yesterday. Tomorrow twilight begins at 6:07 and sunrise is at 6:36. The moon is waxing crescent. Illumination was 5% at midnight, will be 8% at noon and 11% at midnight tonight. Moonrise is at 7:28 this morning. Moonset is at 20:45 tonight. Moonrise is at 7:55 tomorrow morning. Moonlight time is 13 hours, 17 minutes which is 35 minutes longer 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 22 days.