Phoenix weather: Valley under heat warning

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By Catherine Holland By Catherine Holland
By Catherine Holland By Catherine Holland

PHOENIX -- The National Weather Service has issued an Excessive Heat Warning for today and tomorrow for the Valley, most of Maricopa County and portions of Pinal County. 

Afternoon highs will top out near 110 degrees this afternoon in the deserts of the state, while humidity stays high and overnight lows struggle to dip below 90 degrees.  Monsoon moisture has returned to the state, keeping dew points high, and making evaporative coolers ineffective. 

That monsoon moisture wil lead to a better chance of thunderstorms today, especially in the high country.  Heavy rain and lightning will be the biggest threats, along with gusty winds. 

The chances for storms in the Valley are near 20 percent both today and tomorrow, and high temperatures should peak near 108 degrees both days. 

The weekend includes a slight chance of storms, and afternoon highs near 106 degrees. 

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