December 27: ORD

Today is December 27th. It's the 362nd 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 30-year averages are 34 and 19.

On the warm side, in 1982 the high was the record high of 61 with a low of 40. A dozen years later, in 1994, the high was 51 with a low of 29. A decade before that, in 1984, the high was 49 with a low of 30. Three years ago the high was 47 with a low of 32. Two years before that, in 2003, the high was 49 with a low of 28. A dozen years earlier, 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. Other warm lows were 30 last year, 28 two years ago and 27 in 1986. The record warmest low of 51 was set in 1959. 20 of the last 30 highs were 20s (9) and 30s (11). On the warmer side, five highs were 40s, one high was in the 50s and one high was in the 60s. On the colder side, three highs were 10s.

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 low of 29, a five degree spread. In 1973 the high was 35 with a low of 30, a five degree spread. In 1959 the high was 57 with a low of 50, a seven degree spread and a warm day.

More recently, we haven't had any spreads of seven degrees or less (except for 1991 (see above)) or anything 30 degrees or more.

On the cold side, in 2000 the high was 17 with a low of 6. 15 years earlier, in 1985, the high was 22 with a low of 3. Seven years before, in 1978, the high was 22 with a low of 3. 15 years later, in 1993, the high was 18 with a low of 8. Ten years before that, in 1983, the high was 19 with a low of 8. Other cold lows were 7 in 1990 and 8 in 2004. The record low of -10 was set in 1950 and the record coldest high of 3 was set in 1925. 18 of the last 30 lows were 10s (10) and 20s (8). On the colder side, seven lows were in the 0s. On the warmer side, four lows were 30s and one low was in the 40s.

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. Tomorrow twilight begins at 6:50 and sunrise is at 7:22. The new moon is today at 6:22. The moon is waxing crescent. Illumination was 0% at midnight, will be 0% at noon and 1% at midnight tonight. Moonrise was at 7:44 and moonset is at 16:33. Moonrise is at 8:22 tomorrow. Moonlight time is 8 hours, 49 minutes today.

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. More on that tomorrow.

As I write this, we are experiencing a thunderstorm (heavy rain and lots of wind).

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