October 4: ORD

Today is October 4th. It's the 277th day of the year. 88 days remain. It's week 40 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 67 and the normal low is 47. I've calculated the 31-year averages at 65 and 45.

On the warm side, in 2005 the high was 87 with the record warmest low of 71. This was the warmest October 4 in O'Hare's history. The former record warmest low of 69 occurred in 1922. Also, that low of 71 tied October 1, 1971 as the warmest October low ever. Another warm high was 82 three years ago. The record high of 90 was set in 1951. Over the last 31 years, 24 highs (77%) have been: 50s (8) and 60s (16). There were seven highs in the warmer: 70s (5) and 80s (2). There have been just five 80s highs this day in 51 years of record-keeping at O'Hare. The other three are included in the next section.

In looking back through the years to the first October at O'Hare in 1959, the following instances were notable: in 1976 the high was a warm 82. In 1975 the high was 75 with a low of 44, a 31 degree spread. In 1969 the high was 80 with a low of 61, a warm day. In 1968 the low was a cool 35 degrees. In 1967 the high was 87 with a low of 66, a hot day (the second hottest of the date). In 1965 the high was 57 with a low of 33, a cool day. In 1963 the high was 73 with a low of 41, a 32 degree spread. In 1959 the high was 60 with a low of 55, a five degree spread.

More recently, there were large spreads of 36 degrees in 1982 (77/41), 33 degrees in 1987 (69/36), 32 degrees in 1984 (70/38), 31 degrees in 2007 (82/51) and 31 degrees in 1993 (65/34). There were no small spreads of up to seven degrees.

On the cool side, in 1980 the high was 51 with the co-record low of 32. In 1988 the high was 52 with a low of 36. Other cool lows were the other co-record low of 32 in 1989, 34 in 1993 and 35 in 1996. Another cool high was 54 in 1999. 30 of the last 31 lows (97%) were: 30s (11), 40s (9) and 50s (10). One low was in the warmer 70s (71 in 2005). There have been no lows in the 60s over the last 31 years.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:26 and sunrise is at 6:54. Sunset is at 18:30 and twilight ends at 18:58. There's a total of 11 hours, 36 minutes of daylight today and 12 hours, 32 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:27 and sunrise is at 6:55. The moon is waning crescent. Illumination was 18% at midnight, will be 13% at noon and 10% at midnight tonight. Moonrise is at 2:59 this morning. Moonset is at 16:32 this afternoon. Moonrise is at 4:15 tomorrow morning. Moonlight time is 13 hours, 33 minutes which is 45 minutes shorter than yesterday.

Columbus Day is in seven days. -Bernie-