March 9: ORD

Today is March 9th. It's the 69th day of the year. 297 days remain. It's week 10 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. ORD has been the official site of record for Chicago since Thursday, January 17, 1980. Before this, the official site of record 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 44 and the normal low is 27. I've calculated the 33-year averages at 42 and 24.

On the warm side, in 1986 the high was 62 with a low of 38. Two decades later, in 2006, the high was 58 with a low of 38. The other warm highs were 63 in both 1992 and 2000, 62 in 2002 (our most recent 60s high) and 56 in 2007. The other warm low was 39 in 1990. The record high of 69 was set in 1974 at Midway. The record warmest low of 52 occurred way back in 1878, at a time when the official readings were taken adjacent to Lake Michigan. 20 of the past 33 highs (61%) were in the: 30s (13) and 40s (7). On the warm side, nine highs (27%) were in the: 50s (5) and 60s (4). O'Hare's warmest March 9th was in 1977 with a high of 68 and low of 50. O'Hare's other pre-1979 warm high was 68 in 1974. On the cold side, four highs (12%) were in the: 10s (a.k.a. teens) (1) and 20s (3). O'Hare's pre-1979 cold high was 25 in 1960.

In looking back through the years to the first March at O'Hare in 1959, the following instances were notable: In 1978 the high was 37 with a cold low of 9, a cold day. In 1977 the high was 68 with a low of 50, a warm day. In 1975 the high was 32 with a low of 15, a cold day. In 1974 the high was 68 with a low of 39, a warm day and year of the record high of 69 at Midway. In 1973 the high was 40 with a low of 37, a three degree spread. In 1968 the high was 51 with a warm low of 42, a warm day. In 1964 the high was 36 with a low of 32, a four degree spread. In 1962 the high was 36 with a low of 33, a three degree spread. In 1960 the high was 25 with a low of 22, a three degree spread and a cold day. In 1959 the high was a cold 32 with a low of 28, a four degree spread.

More recently, we had a small spread of four degrees in 1999 (31/27). There were three days of large spreads: 41 degrees in 2002 (62/21), 40 degrees in 1992 (63/23) and 35 degrees in 2000 (63/28).

On the cold side, in 2003 the high was the record coldest high of 13 with a low of 6 (our most recent single digit low), a seven degree spread. The former record coldest high of 17 occurred back in 1932. In 1984 the high was 25 with the record low of 5. The record low of 5 originally occurred in 1932. In 1982 the high was 27 with a low of 7. In 1996 the high was 26 with a low of 9. The other cold low was 13 in 1995. The other cold highs were 30 in 2005, 31 in 1999 and 32 in 1983. 19 of the last 33 lows (58%) were in the 20s. On the cold side, seven lows (21%) were in the: single digits (4) and 10s (a.k.a. teens) (3). O'Hare's pre-1979 cold lows were 9 in 1978 and 15 in 1975. Seven lows (21%) were in the warm 30s. O'Hare's pre-1979 warm lows were 50 in 1977, 42 in 1968 and 39 in 1974.

Today is a major day in Chicago's snow history. In 1999, 5 inches fell. This was the fifth of six days in which a total of 18.2 inches fell. In 1998, 10.9 inches fell at Midway and 7 inches fell at O'Hare. The 1998 storm occurred during the morning rush hour. O'Hare was shut down from 6:30 to 10:30 A.M. Hundreds of cars and trucks were stuck in the snow on highways in Indiana. 325,000 customers were without electricity around the Chicago area and in Northwest Indiana.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:47 and sunrise is at 6:15. Sunset is at 17:53 and twilight ends at 18:21. There's a total of 11 hours, 38 minutes of daylight today and 12 hours, 34 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:45 and sunrise is at 6:13. The moon is waning gibbous, having reached the full Worm (a.k.a. Sap) moon yesterday at 3:39. Illumination was 99% at midnight, will be 97% at noon and 95% at midnight tonight. Moonset is at 6:30 this morning. Moonrise is at 19:56 tonight. Moonset is at 7:04 tomorrow morning. Moonlight time is 10 hours, 34 minutes which is 44 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. St. Patrick's Day is in eight days.