May and June are the most pleasant months to visit Nice, as this is when the weather is most pleasant. During the high summer of July and August, the humidity and temperatures get high, and the city itself can be uncomfortable - although relaxing on the beach is a joy. The school holidays are always quite busy in Nice, and the time around the nearby Cannes Film festival, and the Monaco Grand Prix (which both take place around the end of May) tend to be booked up months in advance.
February is a good time to visit for lower prices, and some nice weather, and is also the time when you get to see the carnival.
