November 25: ORD

Today is November 25th. It's the 329th day of the year. 36 days remain. It's week 47 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 43 and the normal low is 28. I've calculated the 33-year averages at 43 and 29.

On the warm side, in 1988 the high was 57 with a low of 42. A decade later, in 1998, the high was 53 with a low of 46, a seven degree spread. The other warm highs were 58 in 2006 and 57 in 1997. The other warm low was 42 in 2001. The record high of 65 was set way back in 1908. The record warmest low of 49 occurred back in 1915. Both records were set at a time when the official readings were taken adjacent to Lake Michigan. The last 60s high that both O'Hare and Midway had was in 1976 at exactly 60 degrees. Rockford had a high of 59 that day. After that warm-up, temperatures plummeted to lows in the single digits (O'Hare had lows of 6, 1 and 6 on the 28th, 29th and 30th in 1976). O'Hare also had a high of 62 in 1966. 31 of the past 33 highs (94%) were in the: 30s (9), 40s (13) and 50s (9). Two highs were in the cold 20s. The only pre-1978 cold 20s high was 28 in 1959.

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1977 the high was 33 with a cold low of 8, a cold day. In 1976 the high was a warm 60 degrees. In 1973 the high was 45 with a low of 39, a six degree spread. In 1972 the high was 37 with a low of 33, a four degree spread. In 1966 the high was a warm 62 with a low of 34, a warm day. In 1965 the low was a warm 42 degrees. In 1964 the high was 52 with a low of 19, a 33 degree spread. In 1961 the high was a warm 55 degrees. In 1960 the high was a warm 56 degrees. In 1959 the high was a cold 28 with a low of 18, a cold day.

More recently, there were no large spreads. There were small spreads of four degrees in 1993 (42/38), five degrees in 1987 (42/37), seven degrees in 1992 (46/39) and seven degrees in 2001 (49/42).

On the cold side, in 1991 the high was the record coldest high of 24 with a low of 13. The former record coldest high of 25 occurred in 1930. In 2005 the high was 27 with a low of 13. The record low of 0 was set in 1950 at Midway. 27 of the last 33 lows (82%) were in the: 20s (14) and 30s (13). Three lows were in the cold 10s (a.k.a. teens) and three were in the warm 40s. The only 0s low in ORD history was 8 in 1977. The only other 40s low was 42 in 1965.

There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2005 the high was 27 with a low of 13, overall 16 degrees BELOW normal. Then in 2006 the high was 58 with a low of 36, overall 11 degrees ABOVE normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:25 and sunrise is at 6:56. Sunset is at 16:25 and twilight ends at 16:56. There's a total of 9 hours, 29 minutes of daylight today and 10 hours, 31 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:26 and sunrise is at 6:57. The moon is new today at 0:10. Illumination was 0% at midnight, will be 0% at noon and 1% at midnight tonight. Moonrise is at 7:25 this morning. Moonset is at 16:52 this afternoon. Moonrise is at 8:29 tomorrow morning. Moonlight time is 9 hours, 27 minutes which is 16 minutes shorter than yesterday. Moonlight time is at it's shortest now.

Cool Fall began November 2 and runs for 29 days through November 30. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 10s and 20s occur infrequently. Pearl Harbor Day is in 12 days.