February 21: ORD

Today is February 21st. It's the 52nd day of the year. 314 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 37 and the normal low is 22. I've calculated the 33-year averages at 39 and 24.

On the warm side, in 1991 the high was 58 (O'Hare's warmest high of the date) with a low of 34. 1991 was also O'Hare's warmest February 21st. In 1980 the high was 46 with a low of 36. The other warm highs were 50 in 2003 and 49 in 1983. The other warm low was 37 in 1985, O'Hare's warmest low of the date. The record high of 67 and record warmest low of 47 were set on the same warm day back in 1930, at a time when the official readings were taken adjacent to Lake Michigan. 28 of the past 33 highs (85%) were in the: 30s (15) and 40s (13). O'Hare had consecutive highs in the 30s & 40s as follows: 12 from 1979 through 1990 and nine from 1992 through 2000. On the warm side, two highs were in the 50s. Prior to 1979, O'Hare had highs of 54 in 1961 and 51 in 1974. On the cold side, three highs were in the 20s. O'Hare's coldest high was 4 in 1963.

In looking back through the years to the first February at O'Hare in 1959, the following instances were notable: In 1978 the high was 25 with a low of 7, a cold day. In 1977 the low was a cold 10 degrees. In 1975 the high was a warm 49 degrees. In 1974 the high was 51 with a low of 36, a warm day. In 1968 the high was 22 with a low of -1, a cold day. In 1967 the high was 25 with a low of 3, a cold day. In 1966 the high was 26 with a cold low of -1, a cold day. In 1965 the low was a cold 7 degrees. In 1964 the low was a cold 10 degrees. In 1963 the high was 4 with a low of -8, a cold day. 1963 was the year of the record coldest high (3 at Midway). In 1961 the high was a warm 54 with a low of 21, a 33 degree spread.

More recently, there were small spreads of three degrees in 2005 (36/33), three degrees two years ago, in 2010 (36/33), five degrees in 2002 (34/29), six degrees in 1985 (43/37) and seven degrees in 1996 (35/28).

On the cold side, in 2001 the high was 21 with a low of 9. In 2008 the high was 23 with a low of 8. Two decades earlier, in 1988, the high was 32 with a low of 1, a 31 degree spread. The record low of -11 was set way back in 1873 at a time when the official readings were taken adjacent to Lake Michigan. The record coldest high of 3 was set in 1963 at Midway. 19 of the last 33 lows (58%) were in the 20s. O'Hare recorded six consecutive 20s lows from 1992 through 1997. Six lows (18%) were in the cold: single digits (3) and 10s (a.k.a. teens) (3). O'Hare's coldest low was -8 in 1963. The only other sub-zero lows were -1 in both 1966 and 1968. 1963 was O'Hare's coldest February 21st as the high was 4 with a low of -8. Eight lows (24%) were in the warm 30s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:13 and sunrise is at 6:42. Sunset is at 17:33 and twilight ends at 18:01. There's a total of 10 hours, 51 minutes of daylight today and 11 hours, 48 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:12 and sunrise is at 6:40. The moon is new today at 16:35. Illumination was 1% at midnight, will be 0% at noon and 0% at midnight tonight. Moonrise was at 6:10 this morning. Moonset is at 17:40 this afternoon. Moonrise is at 6:37 tomorrow morning. Moonlight time is 11 hours, 30 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. Mardi Gras is today. George Washington's Birthday and Ash Wednesday are tomorrow.