December 19: ORD

Today is December 19th. It's the 353rd day of the year. 12 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 33 and the normal low is 19. I've calculated the 32-year averages at 32 and 18.

On the warm side, in 2002 the high was 55 with a low of 34. In 1997 the high was 50 with a low of 31. In 1988 the high was 56 with a low of 23, a 33 degree spread. Other warm lows were 33 in 1993, 31 in 1978 and 31 in 1987. The record high of 64 and record warmest low of 57 were set on the same day way back in 1877. Over the last 32 years, 14 highs (44%) were in the 30s. Nine highs (28%) were in the warmer: 40s (6) and 50s (3). Nine highs (28%) were in the cold: 0s (aka single digits)(1), 10s (aka teens)(7) and 20s (1).

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable: in 1977 the high was 39 with a warm low of 35, a four degree spread. In 1976 the high was 49 with a low of 35, a warm day. In 1973 the high was 30 with a low of 24, a six degree spread. In 1972 the high was 37 with a warm low of 35, a mere two degree spread. In 1970 the high was a warm 46 degrees. In 1968 the high was 47 with a low of 31, a warm day. In 1966 the high was 37 with a warm low of 31, a six degree spread. In 1963 the high was 2 with a low of -14, a cold day. That high of 2 was colder than the record coldest high and the low of -14 equals the record low. In 1962 the high was 45 with a low of 35, a warm day. In 1961 the high was 36 with a low of 30, a six degree spread. In 1960 the high was 24 with a cold low of 5, a cold day. Note the absence of a high in the 50s between 1958 and 1977.

More recently, there were no other large spreads of 30 degrees or more. There were small spreads of three degrees in 1993 (36/33), four degrees last year (33/29), six degrees in 1978 (37/31), six degrees in 1982 (35/29) and six degrees in 1987 (37/31).

On the cold side, in 1983 the high was 6 with the record low of -14. In 2005 the high was 11 with a low of -1. In 1985 the high was 15 with a low of -5. In 1996 the high was 13 with a low of 3. In 1989 the high was 15 with a low of 1. In 1980 the high was 16 with a low of 2. A year later, in 1981, the high was 19 with a low of 1. In 2004 the high was 18 with a low of 4. In 2000 the high was 20 with a low of 7. Another cold low was 6 in 1991. The record coldest high of 5 was set in 1963 at Midway. 15 of the last 32 lows (47%) were 20s. 11 lows (34%) were in the cold: negative 10s (1), negative 0s (2), single digits (7) and 10s (aka teens) (1). Six lows (19%) were in the warmer 30s.

In 1973, O'Hare had 3.5 inches of snow today. This was the seventh day of a string of eight days (through tomorrow) which produced 17.6 inches, or 94% of the month's total of 18.8 inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 6:46 and sunrise was at 7:18. Sunset is at 16:23 and twilight ends at 16:55. There's a total of 9 hours, 5 minutes of daylight today and 10 hours, 9 minutes between twilights. We are losing a minute of daylight per day. Tomorrow twilight begins at 6:46 and sunrise is at 7:18. The moon is waxing gibbous, heading towards the full Cold or Long Nights moon in two days at 2:13. Illumination was 95% at midnight, will be 97% at noon and 99% at midnight tonight. Moonset was at 5:41 this morning. Moonrise is at 14:56 this afternoon. Moonset is at 6:41 tomorrow morning. Moonlight time is 14 hours, 45 minutes which is 15 minutes longer than yesterday and is just about at it's peak.

Christmas Eve is in five days and Christmas Day is in six days. -Bernie-