Understand basement humidity
A cool basement responds differently to ventilation than a heated living room. When warm, humid outdoor air enters and cools, its relative humidity increases. Condensation can form on sufficiently cold surfaces. Continuous summer ventilation is therefore not automatically helpful.
Assessment should consider temperature, humidity history, use and building condition together. A room air sensor does not measure moisture inside masonry. Wet structural elements or recurring problems require professional investigation regardless of air readings.