December 27: ORD

Today is December 27th. It's the 361st day of the year. Four days remain. 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 31 and the normal low is 17. The 32-year averages are 35 and 19.

On the warm side, in 1982 the high was the record high of 61 with a low of 40. Two years ago the high tied the record high at 61 degrees with a low of 32. Also two years ago, I wrote "As I write this, we are experiencing a thunderstorm (heavy rain and lots of wind)." In 1994 the high was 51 with a low of 29. A decade earlier, in 1984, the high was 49 with a low of 30. In 2005 the high was 47 with a low of 32. Two years prior, in 2003, the high was 49 with a low of 28. In 1991 the high was 37 with a low of 34, a three degree spread. Seven years later, in 1998, the high was 45 with a low of 26. Another warm low was 30 three years ago. The record warmest low of 51 was set in 1959. 21 of the last 32 highs (66%) were: 20s (10) and 30s (11). On the warmer side, eight highs (25%) were: 40s (5), 50s (1) and 60s (2). On the cold side, three highs (9%) were 10s (aka teens).

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 9 with a low of -2, a cold day. In 1975 the high was 26 with a low of 22, a four degree spread. In 1974 the high was 34 with a warm low of 29, a five degree spread. In 1973 the high was 35 with a warm low of 30, a five degree spread. In 1971 the high was a warm 47 degrees. In 1968 the high was a warm 43 degrees with a low of 34, a warm day. In 1963 the low was a cold 3 degrees. In 1962 the high was 25 with a cold low of -1, a cold day. In 1959 the high was 57 with a low of 50, a seven degree spread and warm day. In 1958 the high was 44 with a low of 32, a warm day.

More recently, we had a small spread of seven degrees last year (21/14). There were no large spreads of at least 30 degrees or more.

On the cold side, in 2000 the high was 17 with a low of 6. In 1985 the high was 22 with a low of 3. In 1978 the high was 22 with a low of 3. Other cold highs were 18 in 1993 and 19 in 1983. The record low of -10 was first set in 1886 and tied in 1950. The record coldest high of 3 was set in 1925. 26 of the last 32 lows (81%) were: single digits (7), 10s (aka teens) (11) and 20s (8). On the warmer side, six lows were: 30s (5) and 40s (1).

Today is a major snow day in O'Hare's history. Back in 1894 in Chicago at the Auditorium Tower, which was the official reporting site for Chicago, 10.1 inches of snow fell. Back in 1978 tomorrow a major four-day snow of 16.8 inches began. But more on that tomorrow!

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:49 and sunrise is at 7:21. Sunset is at 16:28 and twilight ends at 17:00. There's a total of 9 hours, 7 minutes of daylight today and 10 hours, 11 minutes between twilights. We are gaining a minute of daylight a day. Tomorrow twilight begins at 6:50 and sunrise is at 7:21. The moon reaches last quarter tonight at 22:18. Illumination was 61% at midnight, will be 55% at noon and 49% at midnight tonight. Moonset is at 11:01 this morning. Moonrise is at 0:15 tomorrow morning. Moonset is at 11:30 tomorrow morning. Moonlight time is 11 hours, 1 minute which is 30 minutes shorter than yesterday.

New Year's Eve is in four days and New Year's Day is in five days. -Bernie-