PHOENIX -- It was a hazy start to the last day of spring, but temperatures were mild. Overnight lows dropped to the low 70s in parts of the Valley under a cloudless sky, but a haze of wildfire smoke from the Poco Fire hung near the Valley floor.
Light easterly winds helped import some of that smoke during the overnight and early morning hours. The Arizona Department of Environmental Quality issued a Health Watch for Particulate Matter today. This is on top of an Ozone Health Watch already in effect today for the Valley. Those with sensitive respiratory systems should limit their time outdoors, and everyone is asked to carpool if they can, and refuel after dark.
Look for sunshine and an afternoon high of 110 degrees today, topping out near 111 for the next couple of days with an Excessive Heat Warning in effect Thursday and Friday.
A few changes are forecast for the weekend, including a chance for monsoon thunderstorms.
As our high-pressure ridge shifts east and a low-pressure system moves by to our north, the wind flow turns southerly in Arizona, importing monsoon moisture to the state.
There is a chance of afternoon and evening storms in Southern, Eastern and Northern Arizona Saturday, with a chance for wind and dust in the Valley.
The Valley has a slightly better chance of getting thunderstorms and rain on Sunday and Monday afternoons and evenings. Afternoon temperatures will top out closer to normal Sunday near 107, but will hover near 110 on Saturday.