Amsterdam's climate is mild but changeable year-round. January and February are the chilliest months, with temperatures usually between 30 F/-1 C and 40 F/4 C. Though often windy, it's rare for Amsterdam to get much snow or for the canals to freeze. June-September is warm but generally not hot: Temperatures rarely exceed 80 F/27 C and can get as cool as 50 F/10 C.
The Netherlands is a damp country. The running joke is that it only rains two days a year—the rest of the time it pours. Rain can arrive unexpectedly on what starts out to be a sunny day. Therefore, a raincoat and umbrella are often necessary. In summer, the humidity can become oppressive.