I know how to fix it~
It is normally a weather file that causes this, when you enter the map from Cape Portal.
So, you have two options -
Re-install FH
Or, make another map, just a small one or something, and put a portal there leading to your map, and remove the Cape Portal from your original map.
When you want to enter your original map, you will have to go through the smaller map from Cape, as long as that smaller map has no weather, you should be okay.
Hope this helped!