Your requirement is not clear to me. The semantic content of both lines is the same (Temp: 37.8°F), the rest is just HTML fomatting. Why can you skip the first line but not the second? Schouldn't you look for a way to ignore the <span>-Tag only instead of the whole line? Also I'd recommend a framework for parsing HTML because there may be line breaks that split your line and you may not find it.
Having sad this a look ahead expression may do it:
Thanks for your kid answer. My experience to date with one HTML parsing framework is that it does not live up to the proposed design.
In the meantime, I'll suffice with regular expressions with the aid of my peers.