Possible bad weather end of April, should i cancel a planned trip

Yes, the weather is very changeable at this time of the year anyway, and weather seems even more erratic that year than usual. There is no guarantee of what your weather will be, it might even change again and be sunny. I would always carry a raincoat and wear closed shoes when travelling in northern Europe in Spring. Even if you go to the Netherlands and it does rain, as long as you properly equipped, then the positive is that you are there and have so much to discover and enjoy, regardless of the weather.

One point is that weather forecasts that far out (April 27 is two weeks from now) are not reliable for day-by-day details.

But even that aside, the Netherlands have an oceanic climate, like much of the rest of northern Europe, including the UK and Ireland, most of France, the rest of the Low Countries and western Germany. These climates have relatively even precipitation throughout the year (no dry season), and weather that can change relatively fast. It is somewhat sunnier in the summer but cloudiness is still normal and to be expected at any time of year.

To be blunt, an oceanic climate is not one that offers easily predictable weather at any time of the year, and you shouldn't be planning to a trip to a place like that with an expectation of warm, clear, sunny weather. I'm not saying it doesn't happen of course -- just that at the advance timeframes you're likely planning a European trip there's no way to know what it will be. There's no guarantee that if you reschedule that you will get better weather.

That's they way it goes; just cancel and wait until summer and the outdoor festival season but the flowers will be gone by then. This site has what the recorded temps for like in past years:
https://www.timeanddate.com/weather/netherlands/amsterdam/historic

It is typical spring weather

What's the weather going to be like in "California" (a large area, as is Holland) in two weeks?

Hint: Most modern weather forecasts are generally pretty reliable for about the next 24 hours. Looking ahead 36-72 hours, reliability tends to drop rapidly with each hour you look further ahead. Predicting more than a few days out, you might as well be using a Ouija board, consult an astrologer, or ask a cat. You can look at historical trends, but that only tells you what happened in the past, the future is a lot more cloudy (or sunny, or mixed...).

Imagine the regret you'll feel in 2 weeks if you're sitting at home and the weather forecast has changed yet again. It's much too early to accurately predict.

You should go of course! Its a Northern European destination so unfortunately warm and sunny weather is not guaranteed at any time of the year. If you don’t go now you maybe never will. I doubt it will be very cold. Just wear layers and waterproofs and you’ll be fine.

There is a reason that the Mediterranean resorts are full of Brits, Irish, German and Dutch holidaymakers. If they had sun at home they wouldn’t bother travelling so far!

Our family was in the Netherlands a month ago and the weather cooperated . We’re Californians, too, and were initially concerned about the rain. Then we came to our senses and realized we booked for a country that gets rain in Spring. It rained a few times but we made the most of it and enjoyed it. We all had ponchos and layers. One day our teen thought she didn’t need to take her jacket and she was wrong. She learned (though we had to go back to the hotel midday to get her jacket).

Take ponchos. Know you may get rained on (you could any day). Enjoy tulips. Enjoy Van Gogh. Enjoy the canals. Enjoy Rembrandt. Enjoy apple pie.

We've been in Switzerland for the past two weeks plus and use MeteoBlue every day. We're finding it accurate about half the time! It seems like it is very pessimistic compared to other forecast apps. Often it is sunny when it predicted rain, or there are patches of sun and blue sky when it predicted clouds. As others have said, long-term forecasts almost always change, often several times, and it is best at about 24-hours out. I would have felt terrible if we'd cancelled our trip based on what MeteoBlue said. Instead, almost all of our photos have some patches of sun and blue skies.

Thank you to everyone for all of your information. Much appreciated. My fears have been somewhat assuaged; I was worried about getting a week of nothing but 24hr clouds and no sun. From what I hear though there’s going to be some decent sun, levitating if a bit chilly.

Looking forward to my trip.