Winters in Gennevilliers are cool and relatively mild, with temperatures ranging from around 0°C to 15°C, averaging around 4-6°C. Spring is a gradual warming period, with temperatures slowly increasing from -5°C to highs of 25-27°C by May. Summer months bring warm temperatures, peaking in July at an average of 19°C, but with cooler days still possible. Autumn sees a return to milder conditions, with temperatures dipping back down to around 0-14°C by November and December. Overall, the region's temperature fluctuations are relatively moderate throughout the year, with few extreme variations.