July 30: ORD

Today is July 30th. It's the 211th day of the year. 154 days remain. It's week 31 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 64. I've calculated the 31-year averages at 83 and 63.

On the hot side, in 1999 the high was 101 with a low of 78. Other hot highs were 96 in 1995 and 95 in 1988. The record high of 102 and record warmest low of 84 were set on the same day back in 1916. Another warm low was 77 in 2006. We had very high dew points in 1999. The top was 82 degrees, making 1999 perhaps the most humid July 30 on record. 21 of the last 31 highs were: 70s (10) and 80s (11). Eight highs were in the warmer: 90s (7) and 100s (1). Two highs were in the cooler 60s.

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1971 the high was 72 with a low of 53, a cool day. In 1965 the high was 82 with a cool low of 50, a 32 degree spread. That low of 50 equaled the record low.

More recently, there were large spreads of 32 degrees in 1984 (82/50) and 31 degrees in 2003 (84/53). There were small spreads of five degrees in 1985 (69/64) and six degrees in 2000 (74/68).

On the cool side, in 1992 the high was 65 with a low of 58, a seven degree spread. The coolest low was the record low of 50, set in 1984. Another cool high was 69 in 1985. The record coolest high of 62 occurred way back in 1895. The official thermometer was located near Lake Michigan at the time. 25 of the last 31 lows were: 50s (11) and 60s (14). 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 5:12 and sunrise was at 5:44. Sunset is at 20:15 and civil twilight ends at 20:47. Nautical twilight ends at 21:26 and astronomical twilight ends at 22:11. There's a total of 14 hours, 31 minutes of daylight today and 15 hours, 35 minutes between twilights. We are losing about two minutes of daylight a day. Tomorrow twilight begins at 5:13 and sunrise is at 5:45. The moon is waning gibbous. Illumination was 85% at midnight, will be 81% at noon and 77% at midnight tonight. Moonset was at 10:15 this morning. Moonrise is at 22:01 tonight. Moonset is at 11:15 tomorrow morning. Moonlight time is 12 hours, 14 minutes which is 37 minutes longer than yesterday. -Bernie-