Planning for the weather is a good way to make your trip to Neuilly-sur-Seine relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July, with an average temperature of 19°C, while the coldest months are January and February, with an average of 6°C. The snowiest months in Neuilly-sur-Seine are February, March, January and May, with each month seeing an average of 13 cm of snowfall.