December 14: ORD

Today is December 14th. It's the 348th day of the year. 17 days remain. It's week 50 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 35 and the normal low is 21. I've calculated the 32-year averages at 37 and 23.

On the warm side, in 2006 the high was 50 with a low of 35. In 1993 the high was 44 with a low of 38, a six degree spread. Two years ago the high was 50 with a low of 31. Other warm highs were 47 in both 1988 and a decade later in 1998. Another warm low was 36 in 1999. The record high of 66 and record warmest low of 47 were set on the same day in 1975. Over the last 32 years, 25 highs (78%) were in the: 30s (16) and 40s (9). Our most recent 40s high (40 in 1999) was the last of five straight years of 40s highs from 1995 to 1999. Two highs were in the warmer 50s. Five highs were in the cold: 10s (aka teens)(2) and 20s (3).

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 36 with a low of 33, a mere three degree spread. In 1975 the high was 64 with a low of 44, a warm day, year of the record high and record warmest low. In 1974 the high was 41 with a warm low of 35 degrees, a six degree spread. In 1972 the high was 26 with a cold low of 2, a cold day. In 1965 the high was 35 with a low of 31, a four degree spread. In 1963 the high was 11 with a low of -6, a cold day. In 1962 the high was 26 with a cold low of 2, a cold day. In 1959 the high was 40 with a warm low of 33, a seven degree spread. In 1958 the high was 12 with a low of -3, a cold day.

More recently, there were no large spreads of 30 degrees or more. There were small spreads of four degrees in 1999 (40/36), six degrees in 1992 (32/26), six degrees in 2003 (31/25), seven degrees in 2001 (38/31), seven degrees in 2002 (38/31) and seven degrees in 2005 (35/28).

On the cold side, in 1985 the high was 16 with a low of -8. Four years later, in 1989, the high was 18 with a low of -3. As you can see, the negative lows occurred back in the 1980's. In 2000 the high was 26 with a low of 7. The record low of -9 was set way back in 1901. The record coldest high of 5 occurred way back in 1903. 16 of the last 32 lows (50%) were 20s. Eight lows were in the cold: negative 0s (2), 0s (aka single digits)(1) and 10s (aka teens)(5). Eight lows were in the warmer 30s. Yesterday was the 3rd coldest December 13 of the past 33 years which puts it among the top 9% of coldest days for the date.

In 1973, O'Hare had 0.3 inches of snow today. This was the second day of a string of days through the 20th which produced 17.6 inches, or 94% of the month's total of 18.8 inches. In 1987, O'Hare had 1.1 inches, part of a two-day storm of 9.1 inches. In 1951 Midway had ten inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 6:43 and sunrise was at 7:14. Sunset was at 16:22 and twilight ends at 16:53. There's a total of 9 hours, 8 minutes of daylight today and 10 hours, 10 minutes between twilights. We are losing a minute of daylight per day. Tomorrow twilight begins at 6:43 and sunrise is at 7:15. The moon reached first quarter yesterday morning at 7:59 and is waxing gibbous. Illumination was 56% at midnight, will be 61% at noon and 66% at midnight tonight. Moonset was at 29 minutes past midnight this morning. Moonrise was at 12:06 this afternoon. Moonset is at 1:29 tomorrow morning. Moonlight time is 12 hours, 23 minutes which is 7 minutes longer than yesterday.

Bill of Rights Day is tomorrow. Christmas Eve is in 10 days and Christmas is in 11 days. -Bernie-