December 30: ORD

Today is December 30th. It's the 364th day of the year. One day remains. It's week 52 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. Observations have been official at O'Hare since Thursday, January 17, 1980.

According to the National Climatic Data Center (NCDC), the normal high is 30 and the normal low is 16. I've calculated the 32-year averages at 35 and 20.

On the warm side, in 2002 the high was the near-record high of 60 (our only 60s high) with a low of 37. The record high of 61 was set way back in 1884. A decade earlier, in 1992, the high was 51 with a low of 39. In 2006 the high was 50 with a low of 40. Two years before that, in 2004, the high was 57 with a low of 31. In 1986 the high was 42 with a low of 30. In 2005 the high was 38 with a low of 33, a five degree spread. In 1979 the high was 47 with a low of 23. Another warm high was 42 in 2003. Other warm lows were 32 in 1989, 30 in 1980 and 30 in 1991. The record warmest low of 51 was set way back in 1884. Along with the high of 61, 1884 was the warmest day ever. Back in 1884, the official thermometer was located adjacent to Lake Michigan. 15 of the last 32 highs (47%) were 30s. On the warmer side, nine highs (28%) were: 40s (5), 50s (3) and 60s (1). On the colder side, eight highs (25%) were: 10s (2) and 20s (6).

In looking back through the years to the first December at O'Hare in 1958, the following instances were notable: in 1976 the high was 10 with a low of -2, a cold day. In 1973 the high was a cold 14 degrees with a low of 7, a seven degree spread. In 1972 the high was 48 with a low of 35, a warm day. In 1967 the high was 31 with a low of 25, a six degree spread. In 1965 the high was 57 with a low of 39, one of the warmer days. In 1963 the high was 7 with a low of -12, a cold day. In 1962 the high was a cold 15 with a low of 8, a seven degree spread, a cold day. In 1961 the high was 18 with a low of -2, a cold day. In 1959 the high was 27 with a low of 21, a six degree spread. In 1958 the high was 30 with a low of 23, a seven degree spread.

More recently, we had small spreads of one degree in 1989 (33/32), two degrees in 1980 (32/30) and seven degrees in 1991 (37/30). We've had a couple of large spreads. They are both on the colder side of things. In 1981 the spread was 31 degrees (29/-2) and in 1985 it was 34 degrees (37/3).

On the cold side, in 1983 the high was the near-record coldest high of 10 with the near-record low of -6. The record coldest high of 9 was set back in 1938 and the record low of -7 was set way back in 1909. In 1998 the high was 13 with a low of 1. Other cold lows were -2 in 1981, 3 in 1985 and 3 in 1993. 29 of the last 32 lows (91%) were: single digits (5), 10s (aka teens)(6), 20s (10) and 30s (8). On the colder side, two lows were negative single digits. On the warmer side, one low was in the 40s. Our most recent 20s high (20) and most recent single digit low (5) occurred in 2001.

Today is a major snow day in O'Hare's history. Back in 1978, 1.6 inches fell. This was day three of a four day, 16.8 inch storm. The total snowfall of December 1978 was 35.1 inches at O'Hare.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:50 and sunrise is at 7:22. Sunset is at 16:30 and twilight ends at 17:02. There's a total of 9 hours, 8 minutes of daylight today and 10 hours, 12 minutes between twilights. We are gaining a minute of daylight per day. Tomorrow twilight begins at 6:50 and sunrise is at 7:22. The moon is waning crescent. Illumination was 28% at midnight, will be 23% at noon and 18% at midnight tonight. Moonrise is at 2:40 this morning. Moonset is at 12:36 this afternoon. Moonrise is at 3:50 tomorrow morning. Moonlight time is 9 hours, 56 minutes which is 37 minutes less than yesterday.

New Year's Eve is tomorrow and New Year's Day is in two days. -Bernie-