January 30: ORD

Today is January 30th. It's the 30th day of the year. 336 days remain. It's week 5 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 32 and the normal low is 17. I've calculated the 33-year averages at 29 and 17.

On the warm side, in 1988 the high was the record high of 55 (ties the high of 55 in 1974 as O'Hare's warmest of the date) with the record warmest low of 46. A year later, in 1989, the high was 46 with a low of 35. In 2001 the high was 40 (our most recent 40s high) with a low of 32. Five years later, in 2006, the high was 39 with a low of 32, a seven degree spread. The other warm highs were 45 in 1990 and 44 in 1999. The other warm lows were 31 in 1987, 30 in 1992 and 29 in both 1998 and 2002. 23 of the past 33 highs (70%) were in the: 20s (10) and 30s (13). There were nine consecutive 20s & 30s highs from 1979 through 1987. Before this period, 1978 was a cold day (14/-9). After this period, 1988 was our warmest day (55/46). On the warm side, five highs (15%) were in the: 40s (4) and 50s (1). On the cold side, five highs (15%) were in the: single digits (2) and 10s (a.k.a. teens) (3). O'Hare's coldest high of the date was 2 in 1965. Another pre-1979 cold high was 4 in 1966. The three 10s highs came in the back-to-back-to-back years of 2007, 2008 and 2009. These were the first tens highs since 1978.

In looking back through the years to the first January at O'Hare in 1959, the following instances were notable: In 1978 the high was 14 with a low of -9, a cold day. In 1977 the high was 9 with a low of -1, a cold day. In 1975 the high was 32 with a low of 25, a seven degree spread. In 1974 the high was 55 with a low of 36, a warm day. In 1972 the high was 14 with a low of 0, a cold day. In 1971 the high was 15 with a low of -1, a cold day. In 1969 the high was a warm 46 degrees. In 1968 the high was 40 with a warm low of 32, a warm day. In 1967 the high was 30 with a low of 25, a five degree spread. In 1966 the high was 4 with a low of -19, a cold day. 1966 was the year of the record low of -15 at Midway (which was first set in 1951). The low of -19 at O'Hare was colder than the record low. In 1965 the high was 2 with a low of -13, a cold day. That high of 2 was colder than the record coldest high of 3, first set in 1951 and tied in 2004. In 1964 the high was a warm 44 degrees. In 1963 the high was 10 with a low of -6, a cold day. In 1962 the high was 36 with a cold low of -1, a spread of 37 degrees. In 1961 the high was 21 with a cold low of zero, a cold day. In 1960 the high was 33 with a low of 28, a five degree spread.

More recently, there were small spreads of three degrees in 1987 (34/31), four degrees in 1998 (33/29), four degrees last year, in 2011 (30/26), five degrees in 2002 (34/29) and seven degrees in: 1992 (37/30), 2000 (31/24) and two years ago, in 2010 (25/18).

On the cold side, in 2004 the high was the record coldest high of 3 (tied with 3 in 1951 at Midway) with a low of -9. In 1996 the high was 7 with a low of -4. Four years ago, in 2008, the high was 12 with a low of -2. Three years ago, in 2009, the high was 14 with a low of 4. In 1986 the high was 22 with a low of 0. Five years ago, in 2007, the high was 18 with a low of 7. The other cold low was 5 in 1984. The record low of -15 was set in 1966 and originally in 1951, both at Midway. 24 of the last 33 lows (73%) were in the: single digits (7), 10s (a.k.a. teens) (9) and 20s (8). On the cold side, three lows (9%) were in the negative single digits. O'Hare's coldest readings of the date were -19 in 1966 and -13 in 1965. Six lows (18%) were in the warm: 30s (5) and 40s (1).

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2006 the high was 39 with a low of 32, overall 11.5 degrees ABOVE normal. Then in 2007 the high was 18 with a low of 7, overall 11.5 degrees BELOW normal.

Today is a major day in O'Hare's snow history. Back in 1939 at the University of Chicago, 14.9 inches fell. Ten years ago, in 2002, 4.8 inches fell. This was the first day of a two day, 12 inch storm which was 77% of the month's total of 15.5 inches.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:39 and sunrise is at 7:09. Sunset is at 17:05 and twilight ends at 17:34. There's a total of 9 hours, 56 minutes of daylight today and 10 hours, 55 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 6:38 and sunrise is at 7:08. The moon reaches first quarter tonight at 22:10. Illumination was 41% at midnight, will be 46% at noon and 51% at midnight tonight. Moonrise is at 10:22 this morning. Moonset is at 0:56 tomorrow morning. Moonrise is at 10:55 tomorrow morning. Moonlight time is 13 hours, 38 minutes which is 27 minutes shorter 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. National Freedom Day is in two days. Groundhog Day is in three days.