December 22: ORD

Today is December 22nd. It's the 356th day of the year. Nine days remain. It's week 51 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.

According to the National Climatic Data Center (NCDC), the normal high is 32 and the normal low is 18. I've calculated the 32-year averages at 33 and 19.

On the warm side, in 1979 the high was 50 with a low of 44, a six degree spread. In 2006 the high was 54 with a low of 40. Three years ago, in 2007, the high was 50 with a low of 36. Four years prior, in 2003, the high was 47 with a low of 36. A couple years before that, in 2001, the high was 49 with a low of 33. In 1994 the high was 52 with a low of 27. Other warm highs were 48 in 1982 and 45 in 1988. Other warm lows were 33 in 1997, 31 in 1981 and 30 in 1987. The record high of 57 was set way back in 1875 and tied in 1957. The record warmest low of 50 occurred back in 1941. Over the last 32 years, 19 highs (59%) were in the: 30s (12) and 40s (7). Four highs (13%) were in the warmer 50s. Nine highs (28%) were in the cold: single digits (3), 10s (aka teens) (4) and 20s (2).

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable: in 1974 the high was 42 with a cold low of 3, a 39 degree spread. In 1973 the low was a cold 3 degrees. In 1972 the high was 33 with a warm low of 31, a mere two degree spread. In 1970 the high was 36 with a warm low of 34, a mere two degree spread. In 1965 the high was a warm 46 with a low of 29, a warm day. In 1963 the high was 19 with a low of -13, a 32 degree spread and cold day. In 1961 the high was 35 with a warm low of 31, a four degree spread. In 1960 the high was 4 with a low of -11, a cold day. That high of 4 is just a degree warmer than the record coldest high of 3 which occurred in 1989.

More recently, there was a large spread of 32 degrees in 2005 (38/6). There were small spreads of two degrees in 1981 (33/31), four degrees in 1997 (37/33), five degrees in 2002 (30/25), five degrees last year (32/27) and seven degrees in 1991 (36/29).

On the cold side, in 1989 the high was the record coldest high of 3 with a low of -12. In 2000 the high was 7 with a low of -9. In 1983 the high was 19 with a low of -18, a 37 degree spread. Two years ago the high was 7 with a low of -4. In 1998 the high was 14 with a low of 5. In 2004 the high was 14 with a low of 8. In 1999 the high was 17 with a low of 8. Other cold lows were 5 in 1990 and 6 in 2005. The record low of -21 was set way back in 1872. 26 of the last 32 lows (81%) were: single digits (5), 10s (aka teens) (5), 20s (10) and 30s (6). Our most recent 10s low was 15 in 1995. Four lows were in the cold: negative 10s (2) and negative single digits (2). Two lows were in the warmer 40s.

In the last 12 years, we've seen a wide variance of temperatures. Four days were much above normal (2001, 2003, 2006 and 2007). Five days were much below normal (1998, 1999, 2000, 2004 and 2008). Three days were within normal. Of those, 2002 and 2009 were slightly above normal while 2005 was slightly below normal. We've seen highs in the single digits, teens (10s), 30s, 40s and 50s. Note, no 20s highs in the last 12 years. 1995 produced the most recent at 29 degrees (also our most recent teens (10s) low).

In 1969, O'Hare had 1.2 inches of snow today. This was the second of four days of a total of 13.5 inches of snow.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:47 and sunrise is at 7:19. Sunset is at 16:25 and twilight ends at 16:57. There's a total of 9 hours, 6 minutes of daylight today and 10 hours, 10 minutes between twilights. We are staying at about the same daylight per day. It is the least amount of daylight of the year, at either 9:05 or 9:06. Tomorrow twilight begins at 6:48 and sunrise is at 7:20. The moon reached the full Cold or Long Nights moon yesterday morning at 2:13 and is waning gibbous. Illumination was 99% at midnight, will be 98% at noon and 95% at midnight tonight. Moonset is at 8:22 this morning. Moonrise is at 18:08 this afternoon. Moonset is at 9:02 tomorrow morning. Moonlight time is 14 hours, 14 minutes which is 25 minutes shorter than yesterday. The Winter Solstice was yesterday at 17:38.

Christmas Eve is in two days and Christmas Day is in three days. -Bernie-