July 4: ORD

Today is July 4th. It's the 185th day of the year. 180 days remain. It's week 27 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 83 and the normal low is 62. I've calculated the 31-year averages at 84 and 64.

On the hot side, in 1990 the high was 96 with a low of 77. In 1999 the high was 93 with a low of 79. In 2003 the high was 94 with a low of 73. The other 90s highs were 91 in 1985, 91 in 1994 and 90 in 2002. The other warm lows were 75 in 1993 and 74 in 1994. The record high of 102 was set back in 1911. The record warmest low of 80 occurred back in 1921. 16 of the last 31 highs were 80s. Six highs were in the warmer 90s. Nine highs were in the cooler: 60s (2) and 70s (7).

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1977 the high was 95 with a low of 78, a hot day. In 1972 the high was 66 with a low of 49 (cooler than the record low), a cool day. In 1967 the high was 64 with a low of 50 (tied record low), a cool day. In 1964 the low was a cool 50 (tied record low). In 1963 the high was 79 with a cool low of 46 (cooler than the record low), a 33 degree spread. In 1961 the high was a cool 65 with a low of 60, a five degree spread.

More recently, there were large spreads of: 33 degrees in 1988 (89/56) and 30 degrees in 1985 (91/61).

On the cool side, no days had means of at least 11.5 degrees below normal. The coolest lows were: 51 in 1996 and 52 two years ago. The record low of 50 was set in 1972 at Midway. The cool highs were 66 in 1997 and 69 last year. The record coolest high of 62 occurred back in 1920. 16 of the last 31 lows were 60s. Nine lows were in the cooler 50s and six lows were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 4:48 and sunrise was at 5:22. Sunset is at 20:33 and twilight ends at 21:07. There's a total of 15 hours, 11 minutes of daylight today and 16 hours, 19 minutes between twilights. Tomorrow twilight begins at 4:49 and sunrise is at 5:23. The moon reaches last quarter this morning at 9:35. Illumination was 54% at midnight, will be 49% at noon and 44% at midnight tonight. Moonset is at 13:26 this afternoon. Moonrise is at 20 minutes past midnight tonight. Moonlight time is 13 hours, 26 minutes which is 57 minutes longer than yesterday. Moonlight time increases as the moon wanes, an inverse.

Independence Day is today. - Bernie -