PHOENIX -- We'll end what has been a very hot week with another hot and dry afternoon, but changes are on the horizon.
A strong ridge of high pressure will lead to abundant sunshine and a high of 109 degrees this afternoon in the Valley. Overnight lows will drop to the low 80s under mostly clear skies.
As our high-pressure ridge moves east and a low-pressure system moves by to our north, monsoon moisture will begin to move into Arizona from the south, increasing throughout the weekend.
Isolated thunderstorms are possible today and especially tomorrow in Southern Arizona, with a threat for blowing dust in the Valley on Saturday afternoon and evening. But on Sunday, deeper moisture moves into the state bringing a better chance of storms in the Valley.
Storm and rain chances are at about 30 percent for both Sunday and Monday, with a slight chance of storms Tuesday, too.
Afternoon temperatures will drop off a bit this weekend, with highs around 108 degrees Saturday and 106 degrees on Sunday.
There are no ozone or heat watches today, but there is a Red Flag Warning for much of Northern Arizona between 11 a.m. and 8 p.m.
Look for very low relative humidity and southwesterly winds between 15 and 25 mph, with gusts up to 40 mph.