Heat warning goes into 8th straight day, Arizonans ready for autumn

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PHOENIX, Ariz. – For the eighth day in a row, a chunk of Arizona is sweltering under an excessive heat warning. Originally slated to expire last Thursday night, the National Weather Service has extended it four times. It’s now set to expire Tuesday night.

Sky Harbor International Airport, which is where the official Phoenix temperatures are measured, generally averages 19 days where the high is 110 degrees or more. We’ve already had 28 of those this year. The record, set in 2007, is 32. While we might not break that record, we do have a couple more 110-plus in the forecast so it’s going to be close.

August 2011 is going to go down as the hottest on record.

Weary and wilted Arizonans say they’re ready for the cooler days of autumn.

“I’m tired of it,” said one man who was out for a pre-dawn hike on Piestewa Peak. “It’s been a long summer … hotter than normal. We’re ready to get it over with so we don’t have to get up so early in the morning [to hike].”

A high-pressure system over the Southwest is what drove those temperatures up and kept them well above the seasonal average of 104 for the past week.

One of the things contributing to the extra hot August is the fact that temperatures have not cooled off terribly much at night. In addition to several record highs, including the hottest ever August day – 117 on Friday, we also saw several record and near-record warm lows.

Plan on a high of 110 under sunny skies both Monday and Tuesday.

The dew point was 61 degrees Monday morning, which is considered fairly humid. Not only does it feel sticky outside, but a dew point that high renders evaporative coolers ineffective. In general, once the dew point climbs above 50 degrees, swamp coolers do not work well, forcing people to switch to more expensive air conditioning.

A slight chance of afternoon and evening thunderstorms returns to the forecast Wednesday through the weekend. That coincides with a slight drop in daytime highs.

By the end of the week, we should top out at about 106 degrees, which is just a couple of degrees above the seasonal average. As the daytime highs drop, so will the overnight lows.Those will be in the mid-80s.