5
For sure;
Here is the actual code straight from my custom block. Its saved as html in the options. There's some stuff in this tag that could come out, like allowtransparency/style="background-color:transparent;z-index:4" but I'll leave them just as they are for you to play with.
<div align='center'>
<IFRAME align=center width=100% height=600 scrolling="no" allowtransparency="true" frameborder=0 style="background-color:transparent;z-index:4" src="http://www.wetterzentrale.de/pics/D2u.html" ></IFRAME>
</div>