Fall equinox: Longer nights, cooler temps - East Valley Tribune: News

Fall equinox: Longer nights, cooler temps

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Posted: Sunday, September 23, 2007 3:49 am | Updated: 7:48 pm, Fri Oct 7, 2011.

While you were sleeping, autumn arrived. Neither calendars nor thermometers determine when summer changes to fall; it’s the revolution of the earth. With the sun crossing the celestial equator at 2:51 a.m. today, we’re entering the time of year when the nights grow longer and the weather cools.

SLIDESHOW: See more photos of Hole in the Rock in Papago Buttes

View graphic of changing seasons

What does that mean for you? Quite a bit, if you want a green lawn, a safe commute or an afternoon enjoying a Valley autumn.


The fall equinox has been marked in the Valley for centuries. The long-gone Hohokam tribe fashioned a celestial calendar out of sunlight streaming through Papago Park’s famous Hole in the Rock. That knowledge was necessary, said Roger Lidman, director of the Pueblo Grande Museum, because the Hohokam were a farming people and the success of their crops depended upon timely planting. In this way, Papago Park joins Mexico’s Chichen Itza and England’s Stonehenge as prehistoric sites used for keeping track of time.


Soon after the autumn equinox is when the Valley experiences the year’s last 100-degree day. Sept. 28 is the average date, according to the National Weather Service, although triple-digit temperatures have been recorded as late as Oct. 23 in 2003.

The cooling is more than welcome, considering the summer inflicted upon us highs of 110 or more for 32 days. With the change in the weather, arts and crafts fairs soon will return. One of the first is the Way Out West Oktoberfest, which begins Oct. 5 at Tempe Town Lake.


Driving at this time of year can be hazardous. Because the Valley’s road grid system is aligned with the compass points, some commuters are looking directly into the sunrise in the morning and the sunset on their way home. Some safety tips: Slow down, keep your windshield clean and wear sunglasses.


“Producing quality lawns in the Southwest can be challenging,” warns the Arizona Master Gardener Manual.

And how.

Letting the Bermuda grass be isn’t an option, as it goes dormant in the fall. So we seed with rye grass, which looks fine during the colder months.

Then again, fall also means tree leaves turning color. If you want to see how nature handles the gardening, try the Coconino or Apache-Sitgreaves national forests. The U.S. Forest Service’s “Fall Foliage Hotline” is (800) 354-4595; press 3 at the prompt.

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