January 13: ORD

Today is January 13th. It's the 13th day of the year. 353 days remain. It's week 2 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. Before this, the official site was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 31 and the normal low is 16. I've calculated the 33-year averages at 32 and 17.

On the warm side, in 2006 the high was 49 with a low of 32 (our most recent 40s high and 30s low). In 1995 the high was 38 with a low of 33, a five degree spread. The other warm highs were 47 in 2005, 44 in 1996 and 44 in 1987. The other warm lows were 32 in 2001, 29 in 2007 and 28 in 2008. The record high of 58 and record warmest low of 44 were set back on the same warm day in 1932, at a time when the official readings were taken adjacent to Lake Michigan. 26 of the past 33 highs (79%) were in the: 20s (9) and 30s (17). On the warm side, five highs were in the 40s. O'Hare's warmest highs of the date were 53 in 1960 and 52 in 1961. On the cold side, two were in the 10s (a.k.a. teens). O'Hare's coldest highs were 10 degrees which occurred in 1963 and 1997. The other pre-1979 10s high was 12 in 1975.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: In 1977 the high was 27 with a cold low of -2, a cold day. In 1975 the high was 12 with a low of 3, a cold day. In 1974 the low was a cold 2 degrees. In 1971 the high was 33 with a warm low of 28, a five degree spread. In 1970 the low was a cold 4 degrees. In 1967 the high was 45 with a low of 29, a warm day. In 1965 the low was a cold 2 degrees. In 1963 the high was 10 with a low of -7, a cold day. In 1961 the high was 52 with a low of 29, a warm day. In 1960 the high was 53 with a low of 37, a warm day.

More recently, we had a small spreads of four degrees in 2001 (36/32) and 2007 (33/29). There were large spreads of 32 degrees in 2005 (47/15) and 31 degrees three years ago in 2009 (29/-2).

On the cold side, in 1997 the high was 10 with a low of -4. A year later, in 1998, the high was 15 with a low of -1. A decade earlier, in 1988, the high was 20 with a low of 3. In 1994 the high was 24 with a low of 1 (O'Hare's most recent single digit low). The other cold low was -2 three years ago in 2009. The record low of -9 was set back in 1929 and originally way back in 1888. The record coldest high of -2 was set way back in 1893. The records were set at a time when the official readings were taken adjacent to Lake Michigan. 23 of the last 33 lows (70%) were in the: 10s (14) and 20s (9). Seven lows were in the cold: negative single digits (3) and single digits (4). O'Hare's coldest low of the date was -7 in 1963. The other sub-zero low prior to 1979 was -2 in 1977. Three lows were in the warm 30s. O'Hare's warmest low of the date was 37 in 1960.

There were two instances of back-to-back years in which temperatures were just about as opposite as they can be. In the first instance, in 1987 the high was 44 with a low of 24, overall 10 degrees ABOVE normal. Then in 1988 the high was 20 with a low of 3, overall 12.5 degrees BELOW normal. In the second instance, in 1994 the high was 24 with a low of 1, overall 11.5 degrees BELOW normal. Then in 1995 the high was 38 with a low of 33, overall 11.5 degrees ABOVE normal.

Today is a major day in O'Hare's snow history. In 1979, 15.3 inches fell. This was the third day of a 21.7 inch, seven day storm. Midway had 16.5 inches on this same day.

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 16:44 and twilight ends at 17:15. There's a total of 9 hours, 23 minutes of daylight today and 10 hours, 26 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 6:49 and sunrise is at 7:20. The moon is waning gibbous. Illumination was 83% at midnight, will be 78% at noon and 73% at midnight tonight. Moonset is at 9:28 this morning. Moonrise is at 22:03 tonight. Moonset is at 9:57 tomorrow morning. Moonlight time is 12 hours, 35 minutes which is 42 minutes longer than yesterday.

Winter began December 1st and runs for 102 days through March 11th. High temperatures in this period are usually in the 20s and 30s. Highs in the 40s and 50s occur infrequently. Martin Luther King, Jr. Day is in three days.