July 28: ORD

Today is July 28th. It's the 209th day of the year. 156 days remain. It's week 30 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 84 and the normal low is 64. I've calculated the 31-year averages at 83 and 63.

On the hot side, in 1983 the high was the record high of 100 with a low of 78. Another hot high was 98 in 1988. Another warm low was 74 in 2002. The record warmest low of 84 occurred back in 1916. 17 of the last 31 highs were 80s. Five highs were in the warmer: 90s (4) and 100s (1). Nine highs were in the cooler: 60s (1) and 70s (8). There was a 10 year sub-90 degree period that started in 1989 and went through 1998.

In looking back through the years to the first July at O'Hare in 1959, the following instances were notable: In 1973 the high was a cool 70. In 1962 the high was 67 with a low of 63, a four degree spread.

More recently, there were no small spreads (diurnals of seven degrees or less) or large spreads (diurnals of 30 degrees or more).

On the cool side, in 1981 the high was the record coolest at 66 degrees with a low of 52. This (along with 1962) were the only 60s highs at O'Hare. The record low of 51 was set in 1984. 25 of the last 31 lows (81%) 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 5:10 and sunrise was at 5:42. Sunset is at 20:17 and civil twilight ends at 20:49. Nautical twilight ends at 21:29 and astronomical twilight ends at 22:14. There's a total of 14 hours, 35 minutes of daylight today and 15 hours, 39 minutes between twilights. We are losing about two minutes of daylight a day. Tomorrow twilight begins at 5:11 and sunrise is at 5:43. The moon is waning gibbous. Illumination was 96% at midnight, will be 93% at noon and 91% at midnight tonight. Moonset was at 8:16 this morning. Moonrise is at 21:18 tonight. Moonset is at 9:16 tomorrow morning. Moonlight time is 10 hours, 58 minutes which is 38 minutes longer than yesterday. -Bernie-