Poissy, France experiences a cool and temperate climate with significant seasonal variation. Winters are chilly, with temperatures often below freezing in January (-6°C to 14°C) and December (-5°C to 16°C), but can occasionally rise into the mid-teens. Spring arrives in March, bringing warmer temperatures (4-25°C) that gradually increase throughout the season, peaking in May (12°C). Summer months are mild, with July and August averaging around 19°C, while September sees a slight drop to 17°C. Autumn is relatively cool, with temperatures dropping back down into single digits by November (-3°C to 15°C).