Please be aware that New York has multiple airports and that these results are for all airports serving the city.
The best month to fly between New York and Amsterdam is February and the most expensive month to fly is October. (Average prices, based on 425 datapoints.)
The best day to arrive at New York is Monday and it would be best to avoid Friday, as prices are on average 63.87% higher than on Monday. (Average prices, based on 246 datapoints.)