October 9: ORD

Today is October 9th. It's the 282nd day of the year. 83 days remain. It's week 41 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.

According to the National Climatic Data Center (NCDC), the normal high is 65 and the normal low is 45. I've calculated the 32-year averages at 63 and 45.

On the warm side, last year, in 2010, the high was the record-tying high of 86 (tied 86 in 1949 at Midway) with a low of 55, a 31 degree spread. Some other highs last year: Rockford: 90 (new record), West Chicago: 88, Midway: 87 (broke their own record), NWS/Romeoville: 88, Aurora: 89, DeKalb: 86, Joliet: 90, Northerly Island: 78. In 2001 the high was 73 with a low of 56. In 1997 the high was 75 with a low of 53. Today's high of at least 80 at O'Hare is just the 5th 80s high in O'Hare's history. The other warm lows were 57 in 1982 and 1984. The record warmest low of 68 occurred way back in 1879, a time when the official readings were taken adjacent to Lake Michigan. 29 of the past 32 highs (91%) were in the: 50s (10), 60s (11) and 70s (8). Two highs were in the warm 80s and two were in the cool 40s.

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1978 the high was 73 with a low of 41, a 32 degree spread. In 1973 the high was 81 with a low of 63, a warm day. In 1969 the high was a warm 79 with a low of 40, a 39 degree spread. In 1967 the high was a cool 48 with a low of 37, a cool day. In 1966 the high was a warm 83 with a low of 49, a 34 degree spread. In 1965 the high was 57 with a low of 50, a seven degree spread. In 1964 the high was 44 (year of the record coolest high of 43) with a low of 24 (colder than the record low of 30), a cold day. In 1963 the high was a warm 79 with a low of 41, a 38 degree spread. In 1961 the high was a warm 80 with a low of 56, a warm day.

More recently, there was a large spread of 30 degrees in 1981 (62/32). There were small spreads of three degrees in 1990 (48/45), six degrees in 1983 (56/50) and six degrees in 1984 (63/57).

On the cool side, in 1993 the high was 48 with a low of 32. In 2000 the high was 57 with the record low of 30. The other cold lows were 32 in both 1981 and 1989. Those 32 degree lows were all former record lows. The other cool highs were 48 in 1990, 52 two years ago (in 2009) and 53 in 1986. As you can see, our only two 40s lows occurred in close years, 1990 and 1993. The record coolest high stands at 43, which occurred in 1964 at Midway. 16 of the last 32 lows (50%) were in the 40s. Eight lows (25%) were in the cold 30s. Eight lows (25%) were in the warm 50s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:31 and sunrise is at 6:59. Sunset is at 18:22 and twilight ends at 18:50. There's a total of 11 hours, 23 minutes of daylight today and 12 hours, 19 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:32 and sunrise is at 7:00. The moon is waxing gibbous. Illumination was 93% at midnight, will be 95% at noon and 97% at midnight tonight. Moonset is at 4:42 this morning. Moonrise is at 17:00 this afternoon. Moonset is at 5:41 tomorrow morning. Moonlight time is 11 hours, 42 minutes which is 36 minutes longer than yesterday.

Warm Fall began September 22 and runs for 41 days through November 1. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 30s and 40s occur infrequently. Columbus Day is tomorrow.