The weather in Amsterdam can be quite changeable. One afternoon after visitng several museums we took a boat trip on the canals. As we were coming to a particular spot where you can see the full panoply of roof lines they use in the local architecture the sky darkend to a dramatic shade of blue and the lights on the arches of the bridge - which one wouldn't have noticed before the sky went dark - popped into view. And while it did rain - our touring boat was well prepared for the eventuality with a glass roof.
While There: tour the canals and do the museums - stay at the lovely Ambassade (a group of canalside houses turned into a small hotel) and eat south asian food at a Rijsttafel.