February 27: ORD

Today is February 27th. It's the 58th day of the year. 308 days remain. It's week 9 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 40 and the normal low is 24. I've calculated the 33-year averages at 38 and 23.

On the warm side, in 1981 the high was 60 with a low of 35. Nearly two decades later, in 2000, the high was 52 with a low of 38. The other warm high was 52 in 1998. The other warm low was 38 in 1999. The record high of 75 was set in 1976 at Midway. The record warmest low of 42 occurred way back in 1896, at a time when the official readings were taken adjacent to Lake Michigan. 22 of the past 33 highs (67%) were in the: 30s (13) and 40s (9). On the warm side, four highs (12%) were in the: 50s (3) and 60s (1). O'Hare's warmest day of the date was in 1976 when the high was 71 and low was 38. On the cold side, seven highs (21%) were in the 20s. O'Hare's coldest highs of the date were 23 degrees in both 1963 and 2008.

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 29 with a cold low of 8, a cold day. In 1977 the high was 32 with a low of 26, a six degree spread. In 1976 the high was 71 with a low of 38, a warm day and year of the record high of 75 at Midway. In 1974 the low was a warm 36 degrees. In 1971 the high was 40 with a low of 34, a six degree spread. In 1970 the high was 33 with a low of 27, a six degree spread. In 1967 the high was 34 with a low of 27, a seven degree spread. In 1964 the high was 31 with a cold low of 3, a cold day. In 1963 the high was 23 with a low of 2, a cold day. In 1960 the high was 27 with a low of 8, a cold day.

More recently, we had small spreads of two degrees in 1995 (33/31), three degrees in 1997 (36/33), four degrees in 1984 (29/25), four degrees in 2007 (33/29), six degrees two years ago, in 2010 (34/28) and seven degrees in 1980 (30/23).

On the cold side, in 1994 the high was 27 with a low of -5 (O'Hare's coldest low and coldest day of the date), a 32 degree spread. A year earlier, in 1993, the high was 29 with a low of 6. In 2008 the high was 23 with a low of 15. Nearly two decades earlier, in 1989, the high was 27 with a low of 11. Three years prior, in 1986, the high was 31 with a low of 9. The other cold lows were 10 in 2003 and 12 in 1979. The other cold high was 25 in 2002. The record low of -6 was set way back in 1897, after originally being set in 1879. The record coldest high of 10 occurred way back in 1888. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. 30 of the last 33 lows (91%) were in the: 10s (a.k.a. teens) (8), 20s (14) and 30s (8). O'Hare's warmest lows were all 38 degrees, in 1976, 1999 and 2000 (our most recent 30s low). Two lows were in the cold single digits and one low was in the very cold negative single digits.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:04 and sunrise is at 6:33. Sunset is at 17:40 and twilight ends at 18:09. There's a total of 11 hours, 7 minutes of daylight today and 12 hours, 5 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:03 and sunrise is at 6:31. The moon is waxing crescent. Illumination was 25% at midnight, will be 29% at noon and 33% at midnight tonight. Moonrise is at 8:55 this morning. Moonset is at 23:42 tonight. Moonrise is at 9:30 tomorrow morning. Moonlight time is 14 hours, 47 minutes which is 26 minutes longer than yesterday. Moonlight time is at its peak today.

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 19 days.