please consider making the forecast section a collapsible link. This way the block size will be minimal but users that wish to see the forecast will still be able to 'click for more'.

You can perhaps re-use the code of the nice slide effect used in the DHTML Menu module or the slide/fade effect in the Collapsiblock module?

I am also creating a 'display weather images as a set of overlaid images' feature request issue. Once this is implemented as well, then the main weather info could also be collapsed when the user clicks on the image. All the above features combined with the option to hide the block's title (a.k.a. title = '') will make it possible to have a really minimal weather display.