October 28: ORD

Today is October 28th. It's the 301st day of the year. 64 days remain. It's week 43 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 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 58 and the normal low is 39. I've calculated the 32-year averages at 58 and 39.

On the warm side, in 1999 the high was the record high of 80 (Chicago's only high of 80 or higher) with a low of 48, a 32 degree spread. A decade earlier, in 1989, the high was 74 (our most recent 70s high) with a low of 53. In 1982 the high was 70 with a low of 54. The other warm highs were 73 in 1983 and 71 in 1986. As you can see, all of the 70s highs occurred between 1982 and 1989, at least 22 years ago. The other warm low was 52 in 1991. The record warmest low of 58 was set way back in 1896, a time when the official readings were taken adjacent to Lake Michigan. 14 of the past 32 highs (44%) were in the 50s. 12 highs (38%) were in the warm: 60s (7), 70s (4) and 80s (1). Six highs (18%) were in the cool 40s. Our last 60s high was 61 in 2004.

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 49 with a cold low of 22, a cool day. In 1974 the high was a warm 73 with a low of 50, a warm day. In 1969 the high was 45 with a low of 25, a cold day. In 1968 the high was a cold 44 with a low of 39, a five degree spread. In 1967 the high was a cold 46 degrees. In 1966 the high was a warm 73 with a low of 37, a 36 degree spread. In 1965 the high was 48 with a cold low of 24, a cool day. In 1960 the high was 56 with a low of 49, a seven degree spread. In 1959 the high was 43 with a low of 25, a cold day.

More recently, there were large spreads of 34 degrees in 1981 (65/31) and 30 degrees in 1983 (73/43). There were small spreads of six degrees in 1991 (58/52), seven degrees in 2000 (53/46), seven degrees two years ago, in 2009 (57/50) and seven degrees last year, in 2010 (46/39).

On the cold side, in 1980 the high was 44 with a low of 26. In 1988 the high was 44 with a low of 30. The other cold low was 25 in 1997. The other cold highs were 45 three years ago, in 2008 and 46 last year, in 2010. The record low of 19 and record coldest high of 31 were set on the same cold day back in 1925, a time when the official readings were taken adjacent to Lake Michigan. 26 of the last 32 lows (81%) were in the: 30s (16) and 40s (10). For 11 consecutive years, from 1998 through 2008, lows were in the 30s & 40s. Two lows were in the cold 20s and four were in the warm 50s.

There's an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1988 the high was 44 with a low of 30, overall 11 degrees BELOW normal. Then in 1989 the high was 74 with a low of 53, overall 15.5 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:52 and sunrise is at 7:21. Sunset is at 17:52 and twilight ends at 18:21. There's a total of 10 hours, 31 minutes of daylight today and 11 hours, 29 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:53 and sunrise is at 7:22. The moon is waxing crescent, having passed new two days ago at 14:56. Illumination was 3% at midnight, will be 6% at noon and 9% at midnight tonight. Moonrise is at 9:41 this morning. Moonset is at 19:13 tonight. Moonrise is at 10:49 tomorrow morning. Moonlight time is 9 hours, 32 minutes which is 22 minutes shorter 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. Halloween is in three days. Election Day is in 11 days.