February 25: ORD

Today is February 25th. It's the 56th day of the year. 310 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 39 and the normal low is 23. I've calculated the 33-year averages at 38 and 22.

On the warm side, in 2000 the high was the record high of 72 with a low of 38, a 34 degree spread. 2000 was also O'Hare's second warmest February 25th. The warmest (by half a degree) was in 1976 when the high was 65 (O'Hare's only 60s high of the date) and low of 46 (O'Hare's warmest low of the date). The former record high of 66 occurred in 1932. In 1996 the high was 59 with a low of 33. Three years ago, in 2009, the high was 54 with a low of 35. The other warm highs were 55 in 2001, 52 in 1998 and 52 in 2002. The record warmest low of 52 occurred in 1957 at Midway. 26 of the past 33 highs (79%) were in the: 20s (7), 30s (13) and 40s (6). On the warm side, 6 highs (18%) were in the: 50s (5) and 70s (1). Five of the seven years from 1996 through 2002 were warm days with highs of at least 52 degrees. Prior to 1979, O'Hare had another 50s high of 56 in 1971. On the cold side, one high (3%) was in the: 10s (a.k.a. teens).

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 40 with a low of 33, a seven degree spread. In 1976 the high was 65 with a low of 46, a warm day. In 1974 the high was 27 with a low of 8, a cold day. In 1973 the high was 36 with a low of 30, a six degree spread. In 1971 the high was a warm 56 with a low of 29, a warm day. In 1969 the high was 38 with a low of 31, a seven degree spread. In 1967 the high was 11 with a low of -8, a cold day. In 1965 the high was 21 with a low of 10, a cold day. In 1963 the high was 22 with a low of 3, a cold day. In 1961 the high was 32 with a low of 25, a seven degree spread. In 1960 the high was 28 with a low of 25, a three degree spread.

More recently, we had spreads of three degrees in 1992 (35/32), three degrees in 2008 (34/31), six degrees in 1979 (28/22), six degrees in 1985 (38/32) seven degrees in 2007 (38/31) and seven degrees last year, in 2011 (36/29).

On the cold side, in 2003 the high was 17 with a low of -2. A decade earlier, in 1993, the high was 21 with a low of -2. Three years earlier, in 1990, the high was 21 with a low of 2. A decade earlier, in 1980, the high was 29 with a low of 8. In 1994 the high was 32 with a low of 7. The other cold highs were 27 in both 1988 and 1991. The record low of -9 and record coldest high of 10 occurred on the same cold day way back in 1900, at a time when the official readings were taken adjacent to Lake Michigan. 28 of the last 33 lows (85%) were in the: 10s (a.k.a. teens) (8), 20s (10) and 30s (10). Five lows (15%) were in the cold: negative single digits (2) and single digits (3). O'Hare's coldest February 25th was in 1967 with a high of 11 and low of -8.

Today is a major day in Chicago's snow history. In 1994, 6.7 inches fell. This was the fourth of four days in which 16.1 inches fell. In 1965, 1.5 inches fell. This was the third of three days in which 10.0 inches fell.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:07 and sunrise is at 6:36. Sunset is at 17:38 and twilight ends at 18:06. There's a total of 11 hours, 2 minutes of daylight today and 11 hours, 59 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:06 and sunrise is at 6:34. The moon is waxing crescent. Illumination was 11% at midnight, will be 14% at noon and 17% at midnight tonight. Moonrise is at 7:55 this morning. Moonset is at 21:45 tonight. Moonrise is at 8:23 tomorrow morning. Moonlight time is 13 hours, 50 minutes which is 33 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 21 days.