Low barometric pressure usually signals rainfall, so it normally rains at reduced barometric stress as well. Radon degrees inside a home have a tendency to climb numerous hrs after reduced barometric stress and also high winds occur outside, so it's not really wise to run a radon test right after a website storm.
Opening windows improves air circulation and ventilation, helping move radon out of the house and mixing radon-free outside air with indoor air. Opening basement windows helps reduce negative air pressure, diluting radon with clean outdoor air.