Wifey B: We did our brief tour of Scandinavia last summer and had an incredible tour advisor from this forum, who has even posted in this thread and to whom we're so grateful.
Now, we have weather services but still we find Windy to be an incredible resource and most users only touching the surface of it's capability. Their free is great and premium even better. A few things I'd like to point out.
1. You have three different forecast models to choose from. A few days out they will often have significant differences. We consider the worst forecast in planning.
2. There are many more layers available and some are very useful. For instance, wind and wind gusts, but the ones we find most useful are for waves. The waves are broken down into Wind Waves, Swell 1, Swell 2, and Swell 3. As pointed out above, height without period is of virtually no meaning.
I just did a little exercise of the coast of Paradise, otherwise known as Fort Lauderdale, Sunday at 11 AM. ECMWF has 6' at 8 seconds, GFS has 5' at 9 seconds and Icon has 5' at 7 seconds. All show it from the North. If you look closely and move a few hours, you see that the difference is ECMWF simply has the conditions arriving sooner.
But there is more. Looking at ECMWF, wind waves are N 3' at 4 seconds, not bad but a bit choppy. However, there is a primary swell on top of that which is 5' at 9 seconds. No other swells. The swell is also from the north. A 5' swell at 9 seconds isn't bad at all. Wouldn't concern me at all. Wind waves of 3' at 4 seconds are a bit rough, but I'd just speed up a bit and be fine. However, these combining as they are appearing to do throws an entirely different look and I'd prefer to wait rather than let them double team me.
As a comparison if I was looking at Palm Coast, it shows NE 5' at 8 seconds but only NW 2' of wind waves at 3 seconds, a NE Swell 5' at 9 seconds, and E Swell 1' at 7 seconds. I find the Palm Coast conditions much more acceptable even though at first glance they look much the same. Why? The overriding contributor in Palm Coast is the swell, not the wind waves.
Now I wouldn't head out in either in a 39' CC, but in an 85' MY I'd likely head on out at Palm Coast and wait at Fort Lauderdale. If I was really looking at this I'd research further.
Just pointing out that there's a lot of available information and one needs to learn to use it all together. As to Windy in Scandinavia, found it very accurate and useful.
Someone once said to me, "I can't figure it out. One day 4' is ok and another day it's horrible." I said, "Not all created equal" and laughed but then showed them the underlying data. They'd never looked at periods.
My first time going out off the coast of Washington, I saw the 10' waves forecast and I was concerned but that's when I really learned about Pacific Coast swells and it was nothing. Meanwhile, the Chesapeake can be horrific at 4' and even at 3'. I've seen 3' at 2 and 3 seconds and that's torturous if going slow. It's like someone beating you at 2 second intervals. Actually sending you opposite at 1 second intervals.
At the moment, we're in the Exumas where conditions are 1' at 4 seconds. Been playing around with water toys and the RIB's and exploring small islands. Snacking on leftover chicken at the moment.