Does weather overlay have maximum height defined?
Using the sample of 'Hello World' for the API, and set the height to be 1363px, width 2545px, which is the maximum browser window size for resolution 2560 * 1600.
On chrome, it only shows the weather overlay half way to the middle, and the bottom half doesn't have any weather overlay.
No error messages in the console, and I can see the height is set to 1363 pixels. I attached screenshots for your reference. I'm using Chrome Version 59.0.3071.115 (Official Build) (64-bit)