October 28: ORD

Today is October 28th. It's the 302nd day of the year. 64 days remain. It's week 44 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. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. Before this, 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 33-year averages at 58 and 39.

On the warm side, in 1999 (O'Hare's warmest October 28th) the high was the record high of 80 (Chicago's only 80s high of the date) with a low of 48, a 32 degree spread. A decade earlier, in 1989 (O'Hare's second warmest October 28th), the high was 74 (O'Hare's second hottest high of the date and our most recent 70s high) with a low of 53 (O'Hare's second warmest low of the date). In 1982 the high was 70 with a low of 54 (O'Hare's warmest low of the date). The other warm highs are 73 degrees in 1966, 73 degrees in 1983 and 71 degrees in 1986. As you can see, all of the post-1978 70s highs occurred between 1982 and 1989. The other warm low of 52 degrees occurred in 1991. The record warmest low of 58 degrees was set way back in 1896, at a time when the official readings were taken adjacent to Lake Michigan. 15 of the past 33 highs (46%) were in the 50s. 12 highs (36%) were in the warm: 60s (7), 70s (4) and 80s (1). Six highs (18%) were in the cool 40s. Our most recent 60s high was 61 degrees in 2004. The other warm day was in 1974 as the high was 73 with a low of 50.

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 additional 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 three years ago, in 2009 (57/50) and seven degrees two years ago, in 2010 (46/39).

On the cool side, in 1980 (tied with 1969 as O'Hare's second coolest October 28th) the high was 44 with a low of 26. In 1988 the high was 44 with a low of 30. O'Hare's second coolest highs of the date (44 degrees) were those just mentioned (in 1980 and 1988) and in 1968. The other cold low of 25 degrees occurred in 1997. The other cool highs were 45 degrees in 2008, 46 degrees in 1967 and 46 degrees two years ago in 2010. The record low of 19 degrees and record coolest high of 31 degrees were set on the same cold day back in 1925, at a time when the official readings were taken adjacent to Lake Michigan. 27 of the last 33 lows (82%) were in the: 30s (17) and 40s (10). Our most recent 40s low was 46 degrees in 2004. Two lows were in the cold 20s. Four lows were in the warm 50s, three of them occurring in a ten year span from 1982 through 1991. O'Hare's coolest October 28th was in 1959 as the high was 43 (O'Hare's coolest high of the date) with a low of 25. Tied with 1980 as O'Hare's second coolest October 28th is 1969 (high of 45, low of 25). O'Hare's other cool 10/28 days are: 1976 (high of 49, low of 22) and 1965 (high of 48, low of 24 (O'Hare's second coldest low of the date)).  

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:53 and sunrise is at 7:22. Sunset is at 17:51 and twilight ends at 18:20. There's a total of 10 hours, 29 minutes of daylight today and 11 hours, 27 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:54 and sunrise is at 7:23. The moon is waxing gibbous, heading towards the full Hunter's moon tomorrow at 14:49. Illumination was 98% at midnight, will be 99% at noon and 100% at midnight tonight. Moonset was at 6:15 this morning. Moonrise is at 17:09 this afternoon. Moonset is at 7:14 tomorrow morning. Moonlight time is 13 hours, 6 minutes which is 32 minutes longer than yesterday.

Warm Fall began September 22nd and runs for 41 days through November 1st. 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. Standard Time returns in seven days. Election Day is in nine days.